2021
Qin, Kaiqiang; Holguin, Kathryn; Mohammadiroudbari, Motahareh; Luo, Chao
A conjugated tetracarboxylate anode for stable and sustainable Na-ion batteries Journal Article
In: CHEMICAL COMMUNICATIONS, vol. 57, no. 19, pp. 2360-2363, 2021, ISSN: 1359-7345.
@article{WOS:000625792300003,
title = {A conjugated tetracarboxylate anode for stable and sustainable Na-ion
batteries},
author = {Kaiqiang Qin and Kathryn Holguin and Motahareh Mohammadiroudbari and Chao Luo},
doi = {10.1039/d0cc08273b},
issn = {1359-7345},
year = {2021},
date = {2021-03-01},
journal = {CHEMICAL COMMUNICATIONS},
volume = {57},
number = {19},
pages = {2360-2363},
publisher = {ROYAL SOC CHEMISTRY},
address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS,
ENGLAND},
abstract = {A conjugated tetracarboxylate, 1,2,4,5-benzenetetracarboxylate sodium
salt (Na4C10H2O8), was designed and synthesized as an anode material in
Na-ion batteries (NIBs). This organic compound shows low redox
potentials (similar to 0.65 V), long cycle life (1000 cycles), and fast
charging capability (up to 2 A g(-1)), demonstrating a promising organic
anode for stable and sustainable NIBs.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
salt (Na4C10H2O8), was designed and synthesized as an anode material in
Na-ion batteries (NIBs). This organic compound shows low redox
potentials (similar to 0.65 V), long cycle life (1000 cycles), and fast
charging capability (up to 2 A g(-1)), demonstrating a promising organic
anode for stable and sustainable NIBs.
Aiello, Clarice D.; Awschalom, D. D.; Bernien, Hannes; Brower, Tina; Brown, Kenneth R.; Brun, Todd A.; Caram, Justin R.; Chitambar, Eric; Felice, Rosa Di; Edmonds, Karina Montilla; Fox, Michael F. J.; Haas, Stephan; Holleitner, Alexander W.; Hudson, Eric R.; Hunt, Jeffrey H.; Joynt, Robert; Koziol, Scott; Larsen, M.; Lewandowski, H. J.; McClure, Doug T.; Palsberg, Jen; Passante, Gina; Pudenz, Kristen L.; Richardson, Christopher J. K.; Rosenberg, Jessica L.; Ross, R. S.; Saffman, Mark; Singh, M.; Steuerman, David W.; Stark, Chad; Thijssen, Jos; Vamivakas, A. Nick; Whitfield, James D.; Zwickl, Benjamin M.
Achieving a quantum smart workforce Journal Article
In: QUANTUM SCIENCE AND TECHNOLOGY, vol. 6, no. 3, 2021, ISSN: 2058-9565.
@article{WOS:000665623700001,
title = {Achieving a quantum smart workforce},
author = {Clarice D. Aiello and D. D. Awschalom and Hannes Bernien and Tina Brower and Kenneth R. Brown and Todd A. Brun and Justin R. Caram and Eric Chitambar and Rosa Di Felice and Karina Montilla Edmonds and Michael F. J. Fox and Stephan Haas and Alexander W. Holleitner and Eric R. Hudson and Jeffrey H. Hunt and Robert Joynt and Scott Koziol and M. Larsen and H. J. Lewandowski and Doug T. McClure and Jen Palsberg and Gina Passante and Kristen L. Pudenz and Christopher J. K. Richardson and Jessica L. Rosenberg and R. S. Ross and Mark Saffman and M. Singh and David W. Steuerman and Chad Stark and Jos Thijssen and A. Nick Vamivakas and James D. Whitfield and Benjamin M. Zwickl},
doi = {10.1088/2058-9565/abfa64},
issn = {2058-9565},
year = {2021},
date = {2021-07-01},
journal = {QUANTUM SCIENCE AND TECHNOLOGY},
volume = {6},
number = {3},
publisher = {IOP PUBLISHING LTD},
address = {TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND},
abstract = {Interest in building dedicated quantum information science and
engineering (QISE) education programs has greatly expanded in recent
years. These programs are inherently convergent, complex, often resource
intensive and likely require collaboration with a broad variety of
stakeholders. In order to address this combination of challenges, we
have captured ideas from many members in the community. This manuscript
not only addresses policy makers and funding agencies (both public and
private and from the regional to the international level) but also
contains needs identified by industry leaders and discusses the
difficulties inherent in creating an inclusive QISE curriculum. We
report on the status of eighteen post-secondary education programs in
QISE and provide guidance for building new programs. Lastly, we
encourage the development of a comprehensive strategic plan for quantum
education and workforce development as a means to make the most of the
ongoing substantial investments being made in QISE.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
engineering (QISE) education programs has greatly expanded in recent
years. These programs are inherently convergent, complex, often resource
intensive and likely require collaboration with a broad variety of
stakeholders. In order to address this combination of challenges, we
have captured ideas from many members in the community. This manuscript
not only addresses policy makers and funding agencies (both public and
private and from the regional to the international level) but also
contains needs identified by industry leaders and discusses the
difficulties inherent in creating an inclusive QISE curriculum. We
report on the status of eighteen post-secondary education programs in
QISE and provide guidance for building new programs. Lastly, we
encourage the development of a comprehensive strategic plan for quantum
education and workforce development as a means to make the most of the
ongoing substantial investments being made in QISE.
Khasanov, Rustem; Mazin, Igor I.
Anomalous gap ratio in anisotropic superconductors: Aluminum under pressure Journal Article
In: PHYSICAL REVIEW B, vol. 103, no. 6, 2021, ISSN: 2469-9950.
@article{WOS:000616271200007,
title = {Anomalous gap ratio in anisotropic superconductors: Aluminum under
pressure},
author = {Rustem Khasanov and Igor I. Mazin},
doi = {10.1103/PhysRevB.103.L060502},
issn = {2469-9950},
year = {2021},
date = {2021-02-01},
journal = {PHYSICAL REVIEW B},
volume = {103},
number = {6},
publisher = {AMER PHYSICAL SOC},
address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
abstract = {Pressure dependence of the thermodynamic critical field B-c in elemental
aluminum was studied by means of the muon-spin rotation-relaxation
technique. Pressure enhances the deviation of B-c(T) from parabolic
behavior, expected for a typical type-I superconductor, thus suggesting the weakening of the gap ratio= /k(B)T(c) ( is
the average value of the superconducting energy gap, T-c is the
transition temperature, and k(B) is the Boltzmann constant). With the
pressure increase from 0.0 to similar or equal to 1.6 GPa,
decreases almost linearly from 1.73(1) to 1.67(1). Our results imply,
therefore, that in elemental aluminum, the gap ratiois smaller
than the weak-coupled BCS prediction alpha(BCS) similar or equal to
1.764, and it is even further reduced under pressure.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
aluminum was studied by means of the muon-spin rotation-relaxation
technique. Pressure enhances the deviation of B-c(T) from parabolic
behavior, expected for a typical type-I superconductor, thus suggesting the weakening of the gap ratio <alpha > = <Delta >/k(B)T(c) (<Delta > is
the average value of the superconducting energy gap, T-c is the
transition temperature, and k(B) is the Boltzmann constant). With the
pressure increase from 0.0 to similar or equal to 1.6 GPa, <alpha >
decreases almost linearly from 1.73(1) to 1.67(1). Our results imply,
therefore, that in elemental aluminum, the gap ratio <alpha > is smaller
than the weak-coupled BCS prediction alpha(BCS) similar or equal to
1.764, and it is even further reduced under pressure.
Dally, Rebecca L.; Lynn, Jeffrey W.; Ghimire, Nirmal J.; Michel, Dina; Siegfried, Peter; Mazin, Igor I.
Chiral properties of the zero-field spiral state and field-induced magnetic phases of the itinerant kagome metal YMn6Sn6 Journal Article
In: PHYSICAL REVIEW B, vol. 103, no. 9, 2021, ISSN: 2469-9950.
@article{WOS:000627550500003,
title = {Chiral properties of the zero-field spiral state and field-induced
magnetic phases of the itinerant kagome metal YMn6Sn6},
author = {Rebecca L. Dally and Jeffrey W. Lynn and Nirmal J. Ghimire and Dina Michel and Peter Siegfried and Igor I. Mazin},
doi = {10.1103/PhysRevB.103.094413},
issn = {2469-9950},
year = {2021},
date = {2021-03-01},
journal = {PHYSICAL REVIEW B},
volume = {103},
number = {9},
publisher = {AMER PHYSICAL SOC},
address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
abstract = {Applying a magnetic field in the hexagonal plane of YMn6Sn6 leads to a
complex magnetic phase diagram of commensurate and incommensurate
phases, one of which coexists with the topological Hall effect (THE)
generated by a unique fluctuation-driven mechanism. Using unpolarized
neutron diffraction, we report on the solved magnetic structure for two
previously identified, but unknown, commensurate phases. These include a
low-temperature, high-field fanlike phase and a room-temperature,
low-field canted antiferromagnetic phase. An intermediate incommensurate
phase between the fanlike and forced ferromagnetic phases is also
identified as the last known phase of the in-plane field-temperature
diagram. Additional characterization using synchrotron powder
diffraction reveals extremely high-quality, single-phase crystals, which
suggests that the presence of two incommensurate magnetic structures
throughout much of the phase diagram is an intrinsic property of the
system. Interestingly, polarized neutron diffraction shows that the
centrosymmetric system hosts preferential chirality in the zero-field
double-flat-spiral phase, which, along with the THE, is a topologically
nontrivial characteristic.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
complex magnetic phase diagram of commensurate and incommensurate
phases, one of which coexists with the topological Hall effect (THE)
generated by a unique fluctuation-driven mechanism. Using unpolarized
neutron diffraction, we report on the solved magnetic structure for two
previously identified, but unknown, commensurate phases. These include a
low-temperature, high-field fanlike phase and a room-temperature,
low-field canted antiferromagnetic phase. An intermediate incommensurate
phase between the fanlike and forced ferromagnetic phases is also
identified as the last known phase of the in-plane field-temperature
diagram. Additional characterization using synchrotron powder
diffraction reveals extremely high-quality, single-phase crystals, which
suggests that the presence of two incommensurate magnetic structures
throughout much of the phase diagram is an intrinsic property of the
system. Interestingly, polarized neutron diffraction shows that the
centrosymmetric system hosts preferential chirality in the zero-field
double-flat-spiral phase, which, along with the THE, is a topologically
nontrivial characteristic.
Cress, Cory D.; Wickramaratne, Darshana; Rosenberger, Matthew R.; Hennighausen, Zachariah; Callahan, Patrick G.; LaGasse, Samuel W.; Bernstein, Noam; Erve, Olaf M.; Jonker, Berend T.; Qadri, Syed B.; Prestigiacomo, Joseph C.; Currie, Marc; Mazin, Igor I.; Bennett, Steven P.
Direct-Write of Nanoscale Domains with Tunable Metamagnetic Order in FeRh Thin Films Journal Article
In: ACS APPLIED MATERIALS & INTERFACES, vol. 13, no. 1, pp. 836-847, 2021, ISSN: 1944-8244.
@article{WOS:000611066000078,
title = {Direct-Write of Nanoscale Domains with Tunable Metamagnetic Order in
FeRh Thin Films},
author = {Cory D. Cress and Darshana Wickramaratne and Matthew R. Rosenberger and Zachariah Hennighausen and Patrick G. Callahan and Samuel W. LaGasse and Noam Bernstein and Olaf M. Erve and Berend T. Jonker and Syed B. Qadri and Joseph C. Prestigiacomo and Marc Currie and Igor I. Mazin and Steven P. Bennett},
doi = {10.1021/acsami.0c13565},
issn = {1944-8244},
year = {2021},
date = {2021-01-01},
journal = {ACS APPLIED MATERIALS \& INTERFACES},
volume = {13},
number = {1},
pages = {836-847},
publisher = {AMER CHEMICAL SOC},
address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA},
abstract = {We have directly written nanoscale patterns of magnetic ordering in FeRh
films using focused helium-ion beam irradiation. By varying the dose, we
pattern arrays with metamagnetic transition temperatures that range from
the asgrown film temperature to below room temperature. We employ
transmission electron microscopy, X-ray diffraction, and
temperature-dependent transport measurements to characterize the
as-grown film, and magneto-optic Kerr effect imaging to quantify the He+
irradiation-induced changes to the magnetic order. Moreover, we
demonstrate temperature-dependent optical microscopy and conductive
atomic force microscopy as indirect probes of the metamagnetic
transition that are sensitive to the differences in dielectric
properties and electrical conductivity, respectively, of FeRh in the
antiferromagnetic (AF) and ferromagnetic (FM) states. Using density
functional theory, we quantify strain- and defect-induced changes in
spin-flip energy to understand their influence on the metamagnetic
transition temperature. This work holds promise for in-plane AF-FM
spintronic devices, by reducing the need for multiple patterning steps
or different materials, and potentially eliminating interfacial
polarization losses due to cross material interfacial spin scattering.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
films using focused helium-ion beam irradiation. By varying the dose, we
pattern arrays with metamagnetic transition temperatures that range from
the asgrown film temperature to below room temperature. We employ
transmission electron microscopy, X-ray diffraction, and
temperature-dependent transport measurements to characterize the
as-grown film, and magneto-optic Kerr effect imaging to quantify the He+
irradiation-induced changes to the magnetic order. Moreover, we
demonstrate temperature-dependent optical microscopy and conductive
atomic force microscopy as indirect probes of the metamagnetic
transition that are sensitive to the differences in dielectric
properties and electrical conductivity, respectively, of FeRh in the
antiferromagnetic (AF) and ferromagnetic (FM) states. Using density
functional theory, we quantify strain- and defect-induced changes in
spin-flip energy to understand their influence on the metamagnetic
transition temperature. This work holds promise for in-plane AF-FM
spintronic devices, by reducing the need for multiple patterning steps
or different materials, and potentially eliminating interfacial
polarization losses due to cross material interfacial spin scattering.
Nikolic, Predrag
Dynamics of local magnetic moments induced by itinerant Weyl electrons Journal Article
In: PHYSICAL REVIEW B, vol. 103, no. 15, 2021, ISSN: 2469-9950.
@article{WOS:000646765400002,
title = {Dynamics of local magnetic moments induced by itinerant Weyl electrons},
author = {Predrag Nikolic},
doi = {10.1103/PhysRevB.103.155151},
issn = {2469-9950},
year = {2021},
date = {2021-04-01},
journal = {PHYSICAL REVIEW B},
volume = {103},
number = {15},
publisher = {AMER PHYSICAL SOC},
address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
abstract = {We derive the effective interactions between local magnetic moments
which are mediated by Weyl electrons in magnetic topological semimetals.
The resulting spin dynamics is governed by the induced Heisenberg,
Kitaev, and Dzyaloshinskii-Moriya (DM) interactions with extended range
and oscillatory dependence on the distance between the spins. These
interactions are realized in multiple competing channels shaped by the
multitude of Weyl nodes in the electron spectrum. Microscopic spins need
to be spatially modulated with a channel-dependent wave vector in order
to take advantage of the interactions. The DM vector is parallel to the
displacement between the two interacting spins, and requires the
presence of Weyl electron Fermi surfaces. We also derive the
Weyl-induced chiral three-spin interaction in the presence of an
external magnetic field. This interaction has an extended range as well,
and acts upon the spatially modulated spins in various channels. Its
tendency is to produce a skyrmion lattice or a chiral spin liquid which
exhibits topological Hall effect. Ultimately, the theory developed here
addresses magnetic dynamics in relativistic metals even when chiral
magnetism is microscopically precluded. We discuss insights into the
ordered state of the magnetic Weyl semimetal NdAlSi.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
which are mediated by Weyl electrons in magnetic topological semimetals.
The resulting spin dynamics is governed by the induced Heisenberg,
Kitaev, and Dzyaloshinskii-Moriya (DM) interactions with extended range
and oscillatory dependence on the distance between the spins. These
interactions are realized in multiple competing channels shaped by the
multitude of Weyl nodes in the electron spectrum. Microscopic spins need
to be spatially modulated with a channel-dependent wave vector in order
to take advantage of the interactions. The DM vector is parallel to the
displacement between the two interacting spins, and requires the
presence of Weyl electron Fermi surfaces. We also derive the
Weyl-induced chiral three-spin interaction in the presence of an
external magnetic field. This interaction has an extended range as well,
and acts upon the spatially modulated spins in various channels. Its
tendency is to produce a skyrmion lattice or a chiral spin liquid which
exhibits topological Hall effect. Ultimately, the theory developed here
addresses magnetic dynamics in relativistic metals even when chiral
magnetism is microscopically precluded. We discuss insights into the
ordered state of the magnetic Weyl semimetal NdAlSi.
Kim, Sungmin; Schwenk, Johannes; Walkup, Daniel; Zeng, Yihang; Ghahari, Fereshte; Le, Son T.; Slot, Marlou R.; Berwanger, Julian; Blankenship, Steven R.; Watanabe, Kenji; Taniguchi, Takashi; Giessibl, Franz J.; Zhitenev, Nikolai B.; Dean, Cory R.; Stroscio, Joseph A.
Edge channels of broken-symmetry quantum Hall states in graphene visualized by atomic force microscopy Journal Article
In: NATURE COMMUNICATIONS, vol. 12, no. 1, 2021, ISSN: 2041-1723.
@article{WOS:000658733500020,
title = {Edge channels of broken-symmetry quantum Hall states in graphene
visualized by atomic force microscopy},
author = {Sungmin Kim and Johannes Schwenk and Daniel Walkup and Yihang Zeng and Fereshte Ghahari and Son T. Le and Marlou R. Slot and Julian Berwanger and Steven R. Blankenship and Kenji Watanabe and Takashi Taniguchi and Franz J. Giessibl and Nikolai B. Zhitenev and Cory R. Dean and Joseph A. Stroscio},
doi = {10.1038/s41467-021-22886-7},
issn = {2041-1723},
year = {2021},
date = {2021-05-01},
journal = {NATURE COMMUNICATIONS},
volume = {12},
number = {1},
publisher = {NATURE RESEARCH},
address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY},
abstract = {The quantum Hall (QH) effect, a topologically non-trivial quantum phase,
expanded the concept of topological order in physics bringing into focus
the intimate relation between the ``bulk'' topology and the edge
states. The QH effect in graphene is distinguished by its four-fold
degenerate zero energy Landau level (zLL), where the symmetry is broken
by electron interactions on top of lattice-scale potentials. However,
the broken-symmetry edge states have eluded spatial measurements. In
this article, we spatially map the quantum Hall broken-symmetry edge states comprising the graphene zLL at integer filling factors of nu =0,1
across the quantum Hall edge boundary using high-resolution atomic force
microscopy (AFM) and show a gapped ground state proceeding from the bulk
through to the QH edge boundary. Measurements of the chemical potential
resolve the energies of the four-fold degenerate zLL as a function of
magnetic field and show the interplay of the moire superlattice
potential of the graphene/boron nitride system and spin/valley
symmetry-breaking effects in large magnetic fields.The broken-symmetry
edge states that are the hallmark of the quantum Hall effect in graphene
have eluded spatial measurements. Here, the authors spatially map the
quantum Hall broken-symmetry edge states using atomic force microscopy
and show a gapped ground state proceeding from the bulk through to the
quantum Hall edge boundary.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
expanded the concept of topological order in physics bringing into focus
the intimate relation between the ``bulk'' topology and the edge
states. The QH effect in graphene is distinguished by its four-fold
degenerate zero energy Landau level (zLL), where the symmetry is broken
by electron interactions on top of lattice-scale potentials. However,
the broken-symmetry edge states have eluded spatial measurements. In
this article, we spatially map the quantum Hall broken-symmetry edge states comprising the graphene zLL at integer filling factors of nu =0,1
across the quantum Hall edge boundary using high-resolution atomic force
microscopy (AFM) and show a gapped ground state proceeding from the bulk
through to the QH edge boundary. Measurements of the chemical potential
resolve the energies of the four-fold degenerate zLL as a function of
magnetic field and show the interplay of the moire superlattice
potential of the graphene/boron nitride system and spin/valley
symmetry-breaking effects in large magnetic fields.The broken-symmetry
edge states that are the hallmark of the quantum Hall effect in graphene
have eluded spatial measurements. Here, the authors spatially map the
quantum Hall broken-symmetry edge states using atomic force microscopy
and show a gapped ground state proceeding from the bulk through to the
quantum Hall edge boundary.
Shi, Lawrence; Li, Qiliang
Families of asymmetrically functionalized germanene films as promising quantum spin Hall insulators Journal Article
In: PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 23, no. 5, pp. 3595-3605, 2021, ISSN: 1463-9076.
@article{WOS:000617431500041,
title = {Families of asymmetrically functionalized germanene films as promising
quantum spin Hall insulators},
author = {Lawrence Shi and Qiliang Li},
doi = {10.1039/d0cp06231f},
issn = {1463-9076},
year = {2021},
date = {2021-02-01},
journal = {PHYSICAL CHEMISTRY CHEMICAL PHYSICS},
volume = {23},
number = {5},
pages = {3595-3605},
publisher = {ROYAL SOC CHEMISTRY},
address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS,
ENGLAND},
abstract = {Topological insulators (TIs), exhibiting the quantum spin Hall (QSH)
effect, are promising for developing dissipationless transport devices
that can be realized under a wide range of temperatures. The search for
new two-dimensional (2D) TIs is essential for TIs to be utilized at
room-temperature, with applications in optoelectronics, spintronics, and
magnetic sensors. In this work, we used first-principles calculations to
investigate the geometric, electronic, and topological properties of GeX and GeMX (M = C, N, P, As; X = H, F, Cl, Br, I, O, S, Se, Te). In 26 of
these materials, the QSH effect is demonstrated by a spin-orbit coupling
(SOC) induced large band gap and a band inversion at the Gamma point,
similar to the case of an HgTe quantum well. In addition, engineering
the intra-layer strain of certain GeMX species can transform them from a
regular insulator into a 2D TI. This work demonstrates that asymmetrical
chemical functionalization is a promising method to induce the QSH
effect in 2D hexagonal materials, paving the way for practical
application of TIs in electronics.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
effect, are promising for developing dissipationless transport devices
that can be realized under a wide range of temperatures. The search for
new two-dimensional (2D) TIs is essential for TIs to be utilized at
room-temperature, with applications in optoelectronics, spintronics, and
magnetic sensors. In this work, we used first-principles calculations to
investigate the geometric, electronic, and topological properties of GeX and GeMX (M = C, N, P, As; X = H, F, Cl, Br, I, O, S, Se, Te). In 26 of
these materials, the QSH effect is demonstrated by a spin-orbit coupling
(SOC) induced large band gap and a band inversion at the Gamma point,
similar to the case of an HgTe quantum well. In addition, engineering
the intra-layer strain of certain GeMX species can transform them from a
regular insulator into a 2D TI. This work demonstrates that asymmetrical
chemical functionalization is a promising method to induce the QSH
effect in 2D hexagonal materials, paving the way for practical
application of TIs in electronics.
Choudhary, Kamal; Garrity, Kevin F.; Ghimire, Nirmal J.; Anand, Naween; Tavazza, Francesca
High-throughput search for magnetic topological materials using spin-orbit spillage, machine learning, and experiments Journal Article
In: PHYSICAL REVIEW B, vol. 103, no. 15, 2021, ISSN: 2469-9950.
@article{WOS:000646763400003,
title = {High-throughput search for magnetic topological materials using
spin-orbit spillage, machine learning, and experiments},
author = {Kamal Choudhary and Kevin F. Garrity and Nirmal J. Ghimire and Naween Anand and Francesca Tavazza},
doi = {10.1103/PhysRevB.103.155131},
issn = {2469-9950},
year = {2021},
date = {2021-04-01},
journal = {PHYSICAL REVIEW B},
volume = {103},
number = {15},
publisher = {AMER PHYSICAL SOC},
address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
abstract = {Magnetic topological insulators and semimetals have a variety of
properties that make them attractive for applications, including
spintronics and quantum computation, but very few high-quality candidate
materials are known. In this paper, we use systematic high-throughput
density functional theory calculations to identify magnetic topological
materials from the approximate to 4000 three-dimensional materials in
the JARVIS-DFT database. First, we screen materials with net magnetic
moment >0.5 mu B and spin-orbit spillage (SOS) >0.25, resulting in 25
insulating and 564 metallic candidates. The SOS acts as a signature of
spin-orbit-induced band-inversion. Then we carry out calculations of
Wannier charge centers, Chern numbers, anomalous Hall conductivities,
surface band structures, and Fermi surfaces to determine interesting
topological characteristics of the screened compounds. We also train
machine learning models for predicting the spillages, band gaps, and
magnetic moments of new compounds, to further accelerate the screening
process. We experimentally synthesize and characterize a few candidate
materials to support our theoretical predictions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
properties that make them attractive for applications, including
spintronics and quantum computation, but very few high-quality candidate
materials are known. In this paper, we use systematic high-throughput
density functional theory calculations to identify magnetic topological
materials from the approximate to 4000 three-dimensional materials in
the JARVIS-DFT database. First, we screen materials with net magnetic
moment >0.5 mu B and spin-orbit spillage (SOS) >0.25, resulting in 25
insulating and 564 metallic candidates. The SOS acts as a signature of
spin-orbit-induced band-inversion. Then we carry out calculations of
Wannier charge centers, Chern numbers, anomalous Hall conductivities,
surface band structures, and Fermi surfaces to determine interesting
topological characteristics of the screened compounds. We also train
machine learning models for predicting the spillages, band gaps, and
magnetic moments of new compounds, to further accelerate the screening
process. We experimentally synthesize and characterize a few candidate
materials to support our theoretical predictions.
Yu, Sheng; Wang, Yu; Song, Yuzhen; Xia, Lei; Yang, Xiaolong; Fang, Hui; Li, Qiliang; Li, Xiaoguang
Hole doping induced half-metallic itinerant ferromagnetism and giant magnetoresistance in CrI3 monolayer Journal Article
In: APPLIED SURFACE SCIENCE, vol. 535, 2021, ISSN: 0169-4332.
@article{WOS:000582373900046,
title = {Hole doping induced half-metallic itinerant ferromagnetism and giant
magnetoresistance in CrI3 monolayer},
author = {Sheng Yu and Yu Wang and Yuzhen Song and Lei Xia and Xiaolong Yang and Hui Fang and Qiliang Li and Xiaoguang Li},
doi = {10.1016/j.apsusc.2020.147693},
issn = {0169-4332},
year = {2021},
date = {2021-01-01},
journal = {APPLIED SURFACE SCIENCE},
volume = {535},
publisher = {ELSEVIER},
address = {RADARWEG 29, 1043 NX AMSTERDAM, NETHERLANDS},
abstract = {The exploit of magnetic devices with high magnetoresistance is vital for
the development of magnetic sensing and data storage technologies. Here,
using density functional calculations combined with Monte Carlo
simulations, we explore the magnetic properties and spin-dependent
transport of CrI3 monolayer under an electrostatic hole doping.
Extraordinarily, the magnetoresistance can be controlled over 10(6)%
within a certain doping density range. The hole doping can render CrI3
monolayer half-metallic and nearly 100% spin-polarization at Fermi
energy level can be achieved. Moreover, the hole doping can
significantly enhance the stability of itinerant ferromagnetism. The
Heisenberg exchange parameters can be significantly improved and
meanwhile, the Curie temperature can be boosted to room temperature via
a doping density of 8.49 x 10(14) cm(-2). This study reveals that the
carrier doping engineering can enable two-dimensional CrI3 as a
remarkable material for developing practical and high-performance
spintronic nanodevices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
the development of magnetic sensing and data storage technologies. Here,
using density functional calculations combined with Monte Carlo
simulations, we explore the magnetic properties and spin-dependent
transport of CrI3 monolayer under an electrostatic hole doping.
Extraordinarily, the magnetoresistance can be controlled over 10(6)%
within a certain doping density range. The hole doping can render CrI3
monolayer half-metallic and nearly 100% spin-polarization at Fermi
energy level can be achieved. Moreover, the hole doping can
significantly enhance the stability of itinerant ferromagnetism. The
Heisenberg exchange parameters can be significantly improved and
meanwhile, the Curie temperature can be boosted to room temperature via
a doping density of 8.49 x 10(14) cm(-2). This study reveals that the
carrier doping engineering can enable two-dimensional CrI3 as a
remarkable material for developing practical and high-performance
spintronic nanodevices.
Dally, Rebecca L.; Phelan, Daniel; Bishop, Nicholas; Ghimire, Nirmal J.; Lynn, Jeffrey W.
Isotropic Nature of the Metallic Kagome Ferromagnet Fe3Sn2 at High Temperatures Journal Article
In: CRYSTALS, vol. 11, no. 3, 2021, ISSN: 2073-4352.
@article{WOS:000633580100001,
title = {Isotropic Nature of the Metallic Kagome Ferromagnet Fe3Sn2 at High
Temperatures},
author = {Rebecca L. Dally and Daniel Phelan and Nicholas Bishop and Nirmal J. Ghimire and Jeffrey W. Lynn},
doi = {10.3390/cryst11030307},
issn = {2073-4352},
year = {2021},
date = {2021-03-01},
journal = {CRYSTALS},
volume = {11},
number = {3},
publisher = {MDPI},
address = {ST ALBAN-ANLAGE 66, CH-4052 BASEL, SWITZERLAND},
abstract = {Anisotropy and competing exchange interactions have emerged as two
central ingredients needed for centrosymmetric materials to exhibit
topological spin textures. Fe3Sn2 is thought to have these ingredients
as well, as it has recently been discovered to host room temperature
skyrmionic bubbles with an accompanying topological Hall effect. We
present small-angle inelastic neutron scattering measurements that
unambiguously show that Fe3Sn2 is an isotropic ferromagnet below T-C
approximate to 660 K to at least 480 K-the lower temperature threshold
of our experimental configuration. Fe3Sn2 is known to have competing
magnetic exchange interactions, correlated electron behavior, weak
magnetocrystalline anisotropy, and lattice (spatial) anisotropy; all of
these features are thought to play a role in stabilizing skyrmions in
centrosymmetric systems. Our results reveal that at the elevated
temperatures measured, there is an absence of significant
magnetocrystalline anisotropy and that the system behaves as a nearly
ideal isotropic exchange interaction ferromagnet, with a spin stiffness D(T = 480 K) = 168 meV angstrom(2), which extrapolates to a ground state spin stiffness D(T = 0 K) = 231 meV angstrom(2).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
central ingredients needed for centrosymmetric materials to exhibit
topological spin textures. Fe3Sn2 is thought to have these ingredients
as well, as it has recently been discovered to host room temperature
skyrmionic bubbles with an accompanying topological Hall effect. We
present small-angle inelastic neutron scattering measurements that
unambiguously show that Fe3Sn2 is an isotropic ferromagnet below T-C
approximate to 660 K to at least 480 K-the lower temperature threshold
of our experimental configuration. Fe3Sn2 is known to have competing
magnetic exchange interactions, correlated electron behavior, weak
magnetocrystalline anisotropy, and lattice (spatial) anisotropy; all of
these features are thought to play a role in stabilizing skyrmions in
centrosymmetric systems. Our results reveal that at the elevated
temperatures measured, there is an absence of significant
magnetocrystalline anisotropy and that the system behaves as a nearly
ideal isotropic exchange interaction ferromagnet, with a spin stiffness D(T = 480 K) = 168 meV angstrom(2), which extrapolates to a ground state spin stiffness D(T = 0 K) = 231 meV angstrom(2).
Kim, Minsu; Gu, Min Guk; Jeong, Heeyoung; Song, Eunseok; Jeon, Jun Woo; Huh, Kang-Moo; Kang, Pilgyu; Kim, Sung-Kon; Kim, Byoung Gak
Laser Scribing of Fluorinated Polyimide Films to Generate Microporous Structures for High-Performance Micro-supercapacitor Electrodes Journal Article
In: ACS APPLIED ENERGY MATERIALS, vol. 4, no. 1, pp. 208-214, 2021, ISSN: 2574-0962.
@article{WOS:000613720100025,
title = {Laser Scribing of Fluorinated Polyimide Films to Generate Microporous
Structures for High-Performance Micro-supercapacitor Electrodes},
author = {Minsu Kim and Min Guk Gu and Heeyoung Jeong and Eunseok Song and Jun Woo Jeon and Kang-Moo Huh and Pilgyu Kang and Sung-Kon Kim and Byoung Gak Kim},
doi = {10.1021/acsaem.0c02096},
issn = {2574-0962},
year = {2021},
date = {2021-01-01},
journal = {ACS APPLIED ENERGY MATERIALS},
volume = {4},
number = {1},
pages = {208-214},
publisher = {AMER CHEMICAL SOC},
address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA},
abstract = {Laser-induced graphene (LIG) typically exhibits a mesostructure with a
small specific surface area, which is detrimental to the electrochemical
performance of micro-super-capacitors (MSCs). Herein, 3D nanostructured
LIGs patterned on fluorinated polyimides (fPfs) via a laser photothermal
method are reported. During laser-induced graphitization, a highly
microporous structure in the LIG develops. Consequently, the patterned
LIG (LIG-fPI) exhibits a very large specific surface area (1126.0 m(2) ,
g(-1)) , thereby enhancing its electrochemical performance.
Specifically, in an H2SO4 aqueous electrolyte, the micropatterned
electrode exhibits an exceptional areal capacitance of 110 mF cm(-2)
(determined by cyclic voltammetry), which is 27 times higher than that
of a LIG based on commercial polyimides and at least 7 times higher than
that of current state-of-the-art MSCs. Furthermore, mechanically stable
and flexible LIG-fPI-MSCs with an organic gel polymer electrolyte (working potential = similar to 3 V) show very high power and energy
densities of 0.58 mW cm(-2) and 0.01 mW h cm(-2), respectively. Thus,
these LIGs are promising for application in high-performance MSCs for
flexible microelectronics.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
small specific surface area, which is detrimental to the electrochemical
performance of micro-super-capacitors (MSCs). Herein, 3D nanostructured
LIGs patterned on fluorinated polyimides (fPfs) via a laser photothermal
method are reported. During laser-induced graphitization, a highly
microporous structure in the LIG develops. Consequently, the patterned
LIG (LIG-fPI) exhibits a very large specific surface area (1126.0 m(2) ,
g(-1)) , thereby enhancing its electrochemical performance.
Specifically, in an H2SO4 aqueous electrolyte, the micropatterned
electrode exhibits an exceptional areal capacitance of 110 mF cm(-2)
(determined by cyclic voltammetry), which is 27 times higher than that
of a LIG based on commercial polyimides and at least 7 times higher than
that of current state-of-the-art MSCs. Furthermore, mechanically stable
and flexible LIG-fPI-MSCs with an organic gel polymer electrolyte (working potential = similar to 3 V) show very high power and energy
densities of 0.58 mW cm(-2) and 0.01 mW h cm(-2), respectively. Thus,
these LIGs are promising for application in high-performance MSCs for
flexible microelectronics.
Schnelle, Walter; Prasad, Beluvalli E.; Felser, Claudia; Jansen, Martin; Komleva, Evgenia V.; Streltsov, Sergey V.; Mazin, Igor I.; Khalyavin, Dmitry; Manuel, Pascal; Pal, Sukanya; Muthu, D. V. S.; Sood, A. K.; Klyushina, Ekaterina S.; Lake, Bella; Orain, Jean-Christophe; Luetkens, Hubertus
Magnetic and electronic ordering phenomena in the Ru2O6-layer honeycomb lattice compound AgRuO3 Journal Article
In: PHYSICAL REVIEW B, vol. 103, no. 21, 2021, ISSN: 2469-9950.
@article{WOS:000661189100003,
title = {Magnetic and electronic ordering phenomena in the Ru2O6-layer honeycomb
lattice compound AgRuO3},
author = {Walter Schnelle and Beluvalli E. Prasad and Claudia Felser and Martin Jansen and Evgenia V. Komleva and Sergey V. Streltsov and Igor I. Mazin and Dmitry Khalyavin and Pascal Manuel and Sukanya Pal and D. V. S. Muthu and A. K. Sood and Ekaterina S. Klyushina and Bella Lake and Jean-Christophe Orain and Hubertus Luetkens},
doi = {10.1103/PhysRevB.103.214413},
issn = {2469-9950},
year = {2021},
date = {2021-06-01},
journal = {PHYSICAL REVIEW B},
volume = {103},
number = {21},
publisher = {AMER PHYSICAL SOC},
address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
abstract = {The silver ruthenium oxide AgRuO3 consists of honeycomb Ru25+O62- layers
and can be considered an analogue of SrRu2O6 with a different
intercalation. We present measurements of magnetic susceptibility and
specific heat on AgRuO3 single crystals, which reveal a sharp
antiferromagnetic transition at 342(3) K. The electrical transport in
single crystals of AgRuO3 is determined by a combination of activated
conduction over an intrinsic semiconducting gap of approximate to 100
meV and carriers trapped and thermally released from defects. From
powder neutron diffraction data a Neel-type antiferromagnetic structure
with the Ru moments along the c axis is derived. Raman spectroscopy on
AgRuO3 single crystals and muon spin rotation spectroscopy on powder
samples indicate a further weak phase transition or a crossover in the
temperature range 125-200 K. The transition does not show up in the
magnetic susceptibility, and its origin is argued to be related to
defects but cannot be fully clarified. The experimental findings are
complemented by density-functional-theory-based electronic structure
calculations. It is found that themagnetism in AgRuO3 is similar to that
in SrRu2O6, however, with stronger intralayer and weaker interlayer
magnetic exchange interactions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
and can be considered an analogue of SrRu2O6 with a different
intercalation. We present measurements of magnetic susceptibility and
specific heat on AgRuO3 single crystals, which reveal a sharp
antiferromagnetic transition at 342(3) K. The electrical transport in
single crystals of AgRuO3 is determined by a combination of activated
conduction over an intrinsic semiconducting gap of approximate to 100
meV and carriers trapped and thermally released from defects. From
powder neutron diffraction data a Neel-type antiferromagnetic structure
with the Ru moments along the c axis is derived. Raman spectroscopy on
AgRuO3 single crystals and muon spin rotation spectroscopy on powder
samples indicate a further weak phase transition or a crossover in the
temperature range 125-200 K. The transition does not show up in the
magnetic susceptibility, and its origin is argued to be related to
defects but cannot be fully clarified. The experimental findings are
complemented by density-functional-theory-based electronic structure
calculations. It is found that themagnetism in AgRuO3 is similar to that
in SrRu2O6, however, with stronger intralayer and weaker interlayer
magnetic exchange interactions.
Heinze, L.; Jeschke, H. O.; Mazin, I. I.; Metavitsiadis, A.; Reehuis, M.; Feyerherm, R.; Hoffmann, J. U.; Bartkowiak, M.; Prokhnenko, O.; Wolter, A. U. B.; Ding, X.; Zapf, V. S.; Moya, C. Corvalan; Weickert, F.; Jaime, M.; Rule, K. C.; Menzel, D.; Valenti, R.; Brenig, W.; Suellow, S.
Magnetization Process of Atacamite: A Case of Weakly Coupled S=1/2 Sawtooth Chains Journal Article
In: PHYSICAL REVIEW LETTERS, vol. 126, no. 20, 2021, ISSN: 0031-9007.
@article{WOS:000652839100003,
title = {Magnetization Process of Atacamite: A Case of Weakly Coupled S=1/2
Sawtooth Chains},
author = {L. Heinze and H. O. Jeschke and I. I. Mazin and A. Metavitsiadis and M. Reehuis and R. Feyerherm and J. U. Hoffmann and M. Bartkowiak and O. Prokhnenko and A. U. B. Wolter and X. Ding and V. S. Zapf and C. Corvalan Moya and F. Weickert and M. Jaime and K. C. Rule and D. Menzel and R. Valenti and W. Brenig and S. Suellow},
doi = {10.1103/PhysRevLett.126.207201},
issn = {0031-9007},
year = {2021},
date = {2021-05-01},
journal = {PHYSICAL REVIEW LETTERS},
volume = {126},
number = {20},
publisher = {AMER PHYSICAL SOC},
address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
abstract = {We present a combined experimental and theoretical study of the mineral
atacamite Cu2Cl(OH)(3). Density-functional theory yields a Hamiltonian
describing anisotropic sawtooth chains with weak 3D connections.
Experimentally, we fully characterize the antiferromagnetically ordered
state. Magnetic order shows a complex evolution with the magnetic field,
while, starting at 31.5 T, we observe a plateaulike magnetization at
about M-sat/2. Based on complementary theoretical approaches, we show
that the latter is unrelated to the known magnetization plateau of a
sawtooth chain. Instead, we provide evidence that the magnetization
process in atacamite is a field-driven canting of a 3D network of weakly
coupled sawtooth chains that form giant moments.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
atacamite Cu2Cl(OH)(3). Density-functional theory yields a Hamiltonian
describing anisotropic sawtooth chains with weak 3D connections.
Experimentally, we fully characterize the antiferromagnetically ordered
state. Magnetic order shows a complex evolution with the magnetic field,
while, starting at 31.5 T, we observe a plateaulike magnetization at
about M-sat/2. Based on complementary theoretical approaches, we show
that the latter is unrelated to the known magnetization plateau of a
sawtooth chain. Instead, we provide evidence that the magnetization
process in atacamite is a field-driven canting of a 3D network of weakly
coupled sawtooth chains that form giant moments.
Li, Qianjie; Ji, Shuaishuai; Wang, Dongdong; Zhu, Jiangyuan; Li, Leiyu; Wang, Wei; Zeng, Min; Hou, Zhipeng; Gao, Xingsen; Lu, Xubing; Li, Qiliang; Liu, Jun-Ming
Simultaneously enhanced energy storage density and efficiency in novel BiFeO3-based lead-free ceramic capacitors Journal Article
In: JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, vol. 41, no. 1, pp. 387-393, 2021, ISSN: 0955-2219.
@article{WOS:000582675600041,
title = {Simultaneously enhanced energy storage density and efficiency in novel
BiFeO3-based lead-free ceramic capacitors},
author = {Qianjie Li and Shuaishuai Ji and Dongdong Wang and Jiangyuan Zhu and Leiyu Li and Wei Wang and Min Zeng and Zhipeng Hou and Xingsen Gao and Xubing Lu and Qiliang Li and Jun-Ming Liu},
doi = {10.1016/j.eurceramsoc.2020.08.032},
issn = {0955-2219},
year = {2021},
date = {2021-01-01},
journal = {JOURNAL OF THE EUROPEAN CERAMIC SOCIETY},
volume = {41},
number = {1},
pages = {387-393},
publisher = {ELSEVIER SCI LTD},
address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND},
abstract = {In this work, a series of novel lead-free
(1-x)Bi0.83Sm0.17Fe0.95Sc0.05O3-x(0.85BaTiO(3)-0.15Bi(Mg0.5Zr0.5)O-3) [(1-x)BSFS-x(BT-BMZ)},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
(1-x)Bi0.83Sm0.17Fe0.95Sc0.05O3-x(0.85BaTiO(3)-0.15Bi(Mg0.5Zr0.5)O-3) [(1-x)BSFS-x(BT-BMZ)
Haripriya, G. R.; Heitmann, T. W.; Yadav, D. K.; Kaphle, G. C.; Ghimire, Madhav Prasad; Pradheesh, R.; Joshi, J.; Vora, P.; Sethupathi, K.; Sankaranarayanan, V; Nair, H. S.
Spin reorientation in antiferromagnetic Dy(2)FeCoO(6)double perovskite Journal Article
In: JOURNAL OF PHYSICS-CONDENSED MATTER, vol. 33, no. 2, 2021, ISSN: 0953-8984.
@article{WOS:000577200200001,
title = {Spin reorientation in antiferromagnetic Dy(2)FeCoO(6)double perovskite},
author = {G. R. Haripriya and T. W. Heitmann and D. K. Yadav and G. C. Kaphle and Madhav Prasad Ghimire and R. Pradheesh and J. Joshi and P. Vora and K. Sethupathi and V Sankaranarayanan and H. S. Nair},
doi = {10.1088/1361-648X/abaeaa},
issn = {0953-8984},
year = {2021},
date = {2021-01-01},
journal = {JOURNAL OF PHYSICS-CONDENSED MATTER},
volume = {33},
number = {2},
publisher = {IOP PUBLISHING LTD},
address = {TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND},
abstract = {We explored the electronic and magnetic properties of the lanthanide
double perovskite Dy(2)FeCoO(6)by combining magnetization, Raman and
Mossbauer spectroscopy and neutron diffraction along with density
functional theory (DFT) calculations. Our magnetization measurements
revealed two magnetic phase transitions in Dy2FeCoO6. First, a paramagnetic to antiferromagnetic transition atT(N)= 248 K and subsequently, a spin reorientation transition atT(SR)= 86 K. In
addition, a field-induced magnetic phase transition with a critical
field ofH(c)approximate to 20 kOe is seen at 2 K. Neutron diffraction
data suggested cation-disordered orthorhombic structure for
Dy(2)FeCoO(6)inPnmaspace group which is supported by Raman scattering
results. The magnetic structures ascertained through representational
analysis indicate that atT(N), a paramagnetic state is transformed to
Gamma(5)(Cx,Fy,Az) antiferromagnetic structure while, atT(SR), Fe/Co
moments undergo a spin reorientation to Gamma(3)(Gx,Ay,Fz). The refined
magnetic moment of (Fe/Co) is 1.47(4)mu(B)at 7 K. The antiferromagnetic
structure found experimentally is supported through the DFT calculations
which predict an insulating electronic state in Dy2FeCoO6.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
double perovskite Dy(2)FeCoO(6)by combining magnetization, Raman and
Mossbauer spectroscopy and neutron diffraction along with density
functional theory (DFT) calculations. Our magnetization measurements
revealed two magnetic phase transitions in Dy2FeCoO6. First, a paramagnetic to antiferromagnetic transition atT(N)= 248 K and subsequently, a spin reorientation transition atT(SR)= 86 K. In
addition, a field-induced magnetic phase transition with a critical
field ofH(c)approximate to 20 kOe is seen at 2 K. Neutron diffraction
data suggested cation-disordered orthorhombic structure for
Dy(2)FeCoO(6)inPnmaspace group which is supported by Raman scattering
results. The magnetic structures ascertained through representational
analysis indicate that atT(N), a paramagnetic state is transformed to
Gamma(5)(Cx,Fy,Az) antiferromagnetic structure while, atT(SR), Fe/Co
moments undergo a spin reorientation to Gamma(3)(Gx,Ay,Fz). The refined
magnetic moment of (Fe/Co) is 1.47(4)mu(B)at 7 K. The antiferromagnetic
structure found experimentally is supported through the DFT calculations
which predict an insulating electronic state in Dy2FeCoO6.
Cho, Chullhee; Kang, Pilgyu; Taqieddin, Amir; Jing, Yuhang; Yong, Keong; Kim, Jin Myung; Haque, Md Farhadul; Aluru, Narayana R.; Nam, SungWoo
Strain-resilient electrical functionality in thin-film metal electrodes using two-dimensional interlayers Journal Article
In: NATURE ELECTRONICS, vol. 4, no. 2, pp. 126-133, 2021, ISSN: 2520-1131.
@article{WOS:000613575900001,
title = {Strain-resilient electrical functionality in thin-film metal electrodes
using two-dimensional interlayers},
author = {Chullhee Cho and Pilgyu Kang and Amir Taqieddin and Yuhang Jing and Keong Yong and Jin Myung Kim and Md Farhadul Haque and Narayana R. Aluru and SungWoo Nam},
doi = {10.1038/s41928-021-00538-4, Early Access Date = FEB 2021},
issn = {2520-1131},
year = {2021},
date = {2021-02-01},
journal = {NATURE ELECTRONICS},
volume = {4},
number = {2},
pages = {126-133},
publisher = {NATURE RESEARCH},
address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY},
abstract = {Flexible electrodes that allow electrical conductance to be maintained
during mechanical deformation are required for the development of
wearable electronics. However, flexible electrodes based on metal thin
films on elastomeric substrates can suffer from complete and unexpected
electrical disconnection after the onset of mechanical fracture across
the metal. Here we show that the strain-resilient electrical performance
of thin-film metal electrodes under multimodal deformation can be
enhanced by using a two-dimensional interlayer. Insertion of atomically
thin interlayers-graphene, molybdenum disulfide or hexagonal boron
nitride-induces continuous in-plane crack deflection in thin-film metal
electrodes. This leads to unique electrical characteristics (termed
electrical ductility) in which electrical resistance gradually increases
with strain, creating extended regions of stable resistance. Our
two-dimensional interlayer electrodes can maintain a low electrical
resistance beyond a strain at which conventional metal electrodes would
completely disconnect. We use the approach to create a flexible
electroluminescent light-emitting device with an augmented
strain-resilient electrical functionality and an early damage diagnosis
capability.
Insertion of an atomically thin interlayer, such as graphene, between a
metal thin film and a substrate can be used to create flexible
electrodes with electrical performance that changes only gradually with
strain and is resistant to abrupt mechanical failure.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
during mechanical deformation are required for the development of
wearable electronics. However, flexible electrodes based on metal thin
films on elastomeric substrates can suffer from complete and unexpected
electrical disconnection after the onset of mechanical fracture across
the metal. Here we show that the strain-resilient electrical performance
of thin-film metal electrodes under multimodal deformation can be
enhanced by using a two-dimensional interlayer. Insertion of atomically
thin interlayers-graphene, molybdenum disulfide or hexagonal boron
nitride-induces continuous in-plane crack deflection in thin-film metal
electrodes. This leads to unique electrical characteristics (termed
electrical ductility) in which electrical resistance gradually increases
with strain, creating extended regions of stable resistance. Our
two-dimensional interlayer electrodes can maintain a low electrical
resistance beyond a strain at which conventional metal electrodes would
completely disconnect. We use the approach to create a flexible
electroluminescent light-emitting device with an augmented
strain-resilient electrical functionality and an early damage diagnosis
capability.
Insertion of an atomically thin interlayer, such as graphene, between a
metal thin film and a substrate can be used to create flexible
electrodes with electrical performance that changes only gradually with
strain and is resistant to abrupt mechanical failure.
Qin, Kaiqiang; Holguin, Kathryn; Mohammadiroudbari, Motahareh; Huang, Jinghao; Kim, Eric Young Sam; Hall, Rosemary; Luo, Chao
Strategies in Structure and Electrolyte Design for High-Performance Lithium Metal Batteries Journal Article
In: ADVANCED FUNCTIONAL MATERIALS, vol. 31, no. 15, 2021, ISSN: 1616-301X.
@article{WOS:000615795700001,
title = {Strategies in Structure and Electrolyte Design for High-Performance
Lithium Metal Batteries},
author = {Kaiqiang Qin and Kathryn Holguin and Motahareh Mohammadiroudbari and Jinghao Huang and Eric Young Sam Kim and Rosemary Hall and Chao Luo},
doi = {10.1002/adfm.202009694},
issn = {1616-301X},
year = {2021},
date = {2021-04-01},
journal = {ADVANCED FUNCTIONAL MATERIALS},
volume = {31},
number = {15},
publisher = {WILEY-V C H VERLAG GMBH},
address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY},
abstract = {Lithium metal is the ``holy grail'' anode for next-generation
high-energy rechargeable batteries due to its high capacity and lowest
redox potential among all reported anodes. However, the practical
application of lithium metal batteries (LMBs) is hindered by safety
concerns arising from uncontrollable Li dendrite growth and infinite
volume change during the lithium plating and stripping process. The
formation of stable solid electrolyte interphase (SEI) and the
construction of robust 3D porous current collectors are effective
approaches to overcoming the challenges of Li metal anode and promoting
the practical application of LMBs. In this review, four strategies in
structure and electrolyte design for high-performance Li metal anode,
including surface coating, porous current collector, liquid electrolyte,
and solid-state electrolyte are summarized. The challenges,
opportunities, perspectives on future directions, and outlook for
practical applications of Li metal anode, are also discussed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
high-energy rechargeable batteries due to its high capacity and lowest
redox potential among all reported anodes. However, the practical
application of lithium metal batteries (LMBs) is hindered by safety
concerns arising from uncontrollable Li dendrite growth and infinite
volume change during the lithium plating and stripping process. The
formation of stable solid electrolyte interphase (SEI) and the
construction of robust 3D porous current collectors are effective
approaches to overcoming the challenges of Li metal anode and promoting
the practical application of LMBs. In this review, four strategies in
structure and electrolyte design for high-performance Li metal anode,
including surface coating, porous current collector, liquid electrolyte,
and solid-state electrolyte are summarized. The challenges,
opportunities, perspectives on future directions, and outlook for
practical applications of Li metal anode, are also discussed.
2020
Schwenk, Johannes; Kim, Sungmin; Berwanger, Julian; Ghahari, Fereshte; Walkup, Daniel; Slot, Marlou R.; Le, Son T.; Cullen, William G.; Blankenship, Steven R.; Vranjkovic, Sasa; Hug, Hans J.; Kuk, Young; Giessibl, Franz J.; Stroscio, Joseph A.
In: REVIEW OF SCIENTIFIC INSTRUMENTS, vol. 91, no. 7, 2020, ISSN: 0034-6748.
@article{WOS:000550071000001,
title = {Achieving mu eV tunneling resolution in an in-operando scanning
tunneling microscopy, atomic force microscopy, and magnetotransport
system for quantum materials research},
author = {Johannes Schwenk and Sungmin Kim and Julian Berwanger and Fereshte Ghahari and Daniel Walkup and Marlou R. Slot and Son T. Le and William G. Cullen and Steven R. Blankenship and Sasa Vranjkovic and Hans J. Hug and Young Kuk and Franz J. Giessibl and Joseph A. Stroscio},
doi = {10.1063/5.0005320},
issn = {0034-6748},
year = {2020},
date = {2020-07-01},
journal = {REVIEW OF SCIENTIFIC INSTRUMENTS},
volume = {91},
number = {7},
publisher = {AMER INST PHYSICS},
address = {1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA},
abstract = {Research in new quantum materials requires multi-mode measurements
spanning length scales, correlations of atomic-scale variables with a
macroscopic function, and spectroscopic energy resolution obtainable
only at millikelvin temperatures, typically in a dilution refrigerator.
In this article, we describe a multi-mode instrument achieving a mu eV
tunneling resolution with in-operando measurement capabilities of
scanning tunneling microscopy, atomic force microscopy, and
magnetotransport inside a dilution refrigerator operating at 10 mK. We
describe the system in detail including a new scanning probe microscope
module design and sample and tip transport systems, along with wiring,
radio-frequency filtering, and electronics. Extensive benchmarking
measurements were performed using
superconductor-insulator-superconductor tunnel junctions, with Josephson
tunneling as a noise metering detector. After extensive testing and
optimization, we have achieved less than 8 mu eV instrument resolving
capability for tunneling spectroscopy, which is 5-10 times better than
previous instrument reports and comparable to the quantum and thermal
limits set by the operating temperature at 10 mK.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
spanning length scales, correlations of atomic-scale variables with a
macroscopic function, and spectroscopic energy resolution obtainable
only at millikelvin temperatures, typically in a dilution refrigerator.
In this article, we describe a multi-mode instrument achieving a mu eV
tunneling resolution with in-operando measurement capabilities of
scanning tunneling microscopy, atomic force microscopy, and
magnetotransport inside a dilution refrigerator operating at 10 mK. We
describe the system in detail including a new scanning probe microscope
module design and sample and tip transport systems, along with wiring,
radio-frequency filtering, and electronics. Extensive benchmarking
measurements were performed using
superconductor-insulator-superconductor tunnel junctions, with Josephson
tunneling as a noise metering detector. After extensive testing and
optimization, we have achieved less than 8 mu eV instrument resolving
capability for tunneling spectroscopy, which is 5-10 times better than
previous instrument reports and comparable to the quantum and thermal
limits set by the operating temperature at 10 mK.
Zhan, Wenqiang; Xiao, Changshi; Wen, Yuanqiao; Zhou, Chunhui; Yuan, Haiwen; Xiu, Supu; Zou, Xiong; Xie, Cheng; Li, Qiliang
Adaptive Semantic Segmentation for Unmanned Surface Vehicle Navigation Journal Article
In: ELECTRONICS, vol. 9, no. 2, 2020.
@article{ISI:000518412200013,
title = {Adaptive Semantic Segmentation for Unmanned Surface Vehicle Navigation},
author = {Wenqiang Zhan and Changshi Xiao and Yuanqiao Wen and Chunhui Zhou and Haiwen Yuan and Supu Xiu and Xiong Zou and Cheng Xie and Qiliang Li},
doi = {10.3390/electronics9020213},
year = {2020},
date = {2020-02-01},
journal = {ELECTRONICS},
volume = {9},
number = {2},
publisher = {MDPI},
address = {ST ALBAN-ANLAGE 66, CH-4052 BASEL, SWITZERLAND},
abstract = {The intelligentization of unmanned surface vehicles (USVs) has recently
attracted intensive interest. Visual perception of the water scenes is
critical for the autonomous navigation of USVs. In this paper, an
adaptive semantic segmentation method is proposed to recognize the water
scenes. A semantic segmentation network model is designed to classify
each pixel of an image into water, land or sky. The segmentation result
is refined by the conditional random field (CRF) method. It is further
improved accordingly by referring to the superpixel map. A weight map is
generated based on the prediction confidence. The network trains itself
with the refined pseudo label and the weight map. A set of experiments
were designed to evaluate the proposed method. The experimental results
show that the proposed method exhibits excellent performance with
few-shot learning and is quite adaptable to a new environment, very
efficient for limited manual labeled data utilization.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
attracted intensive interest. Visual perception of the water scenes is
critical for the autonomous navigation of USVs. In this paper, an
adaptive semantic segmentation method is proposed to recognize the water
scenes. A semantic segmentation network model is designed to classify
each pixel of an image into water, land or sky. The segmentation result
is refined by the conditional random field (CRF) method. It is further
improved accordingly by referring to the superpixel map. A weight map is
generated based on the prediction confidence. The network trains itself
with the refined pseudo label and the weight map. A set of experiments
were designed to evaluate the proposed method. The experimental results
show that the proposed method exhibits excellent performance with
few-shot learning and is quite adaptable to a new environment, very
efficient for limited manual labeled data utilization.
Fox, Joshua J.; Bachu, Saiphaneendra; Cavalero, Randal L.; Lavelle, Robert M.; Oliver, Sean M.; Yee, Sam; Vora, Patrick M.; Alem, Nasim; Snyder, David W.
Chemical vapor transport synthesis, characterization and compositional tuning of ZrSxSe2-x for optoelectronic applications Journal Article
In: JOURNAL OF CRYSTAL GROWTH, vol. 542, 2020, ISSN: 0022-0248.
@article{WOS:000536902200005,
title = {Chemical vapor transport synthesis, characterization and compositional
tuning of ZrSxSe2-x for optoelectronic applications},
author = {Joshua J. Fox and Saiphaneendra Bachu and Randal L. Cavalero and Robert M. Lavelle and Sean M. Oliver and Sam Yee and Patrick M. Vora and Nasim Alem and David W. Snyder},
doi = {10.1016/j.jcrysgro.2020.125609},
issn = {0022-0248},
year = {2020},
date = {2020-07-01},
journal = {JOURNAL OF CRYSTAL GROWTH},
volume = {542},
publisher = {ELSEVIER},
address = {RADARWEG 29, 1043 NX AMSTERDAM, NETHERLANDS},
abstract = {ZrS2, ZrSe2 and mixed alloy ZrSxSe2-x materials were achieved through
chemical vapor transport. The incongruent melting system of Zr-S-Se
formed crystalline layered flakes as a transport product that grew up to
2 cm in lateral size with cm-scale flakes consistently obtained for the
entire compositional range exhibiting visible hexagonal features. Bulk flakes of the series ZrSxSe2-x (x = 0, 0.15, 0.3, 0.6, 1.05, 1.14, 1.51,
1.8 and 2) were analyzed through Raman spectroscopy revealing
significant convolution of primary bonding modes and shifting of Raman
features as a function of increasing sulfur composition. Additionally,
activation of new modes not present in the pure compounds are observed
as effects which result from disorder introduced into the crystal due to
the random mixing of S-Se in the alloying process. Further structural
characterization was performed via x-ray diffraction (XRD) on the
layered flakes to evaluate the progression of layer spacing function of
alloy composition which was found to range between 6.24 angstrom for
ZrSe2 and 5.85 angstrom for ZrS2. Estimation of the compositional ratios
of the alloy flakes through energy dispersive spectroscopy (EDS)
large-area mapping verified the relation of the targeted source
stoichiometry represented in the layered flakes. Atomic-resolution high
angle annular dark field (HAADF)-scanning transmission electron
microscopy (STEM) imaging was performed on the representative Zr
(S0.5Se0.5)(2) alloy to validate the 1T atomic structure and observe the
arrangement of the chalcogenide columns stacks. Additionally, selected
area diffraction pattern generated from the [0 0 0 1] zone axis
revealed the in-plane lattice parameter to be approximately 3.715
angstrom.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
chemical vapor transport. The incongruent melting system of Zr-S-Se
formed crystalline layered flakes as a transport product that grew up to
2 cm in lateral size with cm-scale flakes consistently obtained for the
entire compositional range exhibiting visible hexagonal features. Bulk flakes of the series ZrSxSe2-x (x = 0, 0.15, 0.3, 0.6, 1.05, 1.14, 1.51,
1.8 and 2) were analyzed through Raman spectroscopy revealing
significant convolution of primary bonding modes and shifting of Raman
features as a function of increasing sulfur composition. Additionally,
activation of new modes not present in the pure compounds are observed
as effects which result from disorder introduced into the crystal due to
the random mixing of S-Se in the alloying process. Further structural
characterization was performed via x-ray diffraction (XRD) on the
layered flakes to evaluate the progression of layer spacing function of
alloy composition which was found to range between 6.24 angstrom for
ZrSe2 and 5.85 angstrom for ZrS2. Estimation of the compositional ratios
of the alloy flakes through energy dispersive spectroscopy (EDS)
large-area mapping verified the relation of the targeted source
stoichiometry represented in the layered flakes. Atomic-resolution high
angle annular dark field (HAADF)-scanning transmission electron
microscopy (STEM) imaging was performed on the representative Zr
(S0.5Se0.5)(2) alloy to validate the 1T atomic structure and observe the
arrangement of the chalcogenide columns stacks. Additionally, selected
area diffraction pattern generated from the [0 0 0 1] zone axis
revealed the in-plane lattice parameter to be approximately 3.715
angstrom.
Ghimire, Nirmal J.; Dally, Rebecca L.; Poudel, L.; Jones, D. C.; Michel, D.; Magar, N. Thapa; Bleuel, M.; McGuire, Michael A.; Jiang, J. S.; Mitchell, J. F.; Lynn, Jeffrey W.; Mazin, I. I.
Competing magnetic phases and fluctuation-driven scalar spin chirality in the kagome metal YMn6Sn6 Journal Article
In: SCIENCE ADVANCES, vol. 6, no. 51, 2020, ISSN: 2375-2548.
@article{WOS:000599905500047,
title = {Competing magnetic phases and fluctuation-driven scalar spin chirality
in the kagome metal YMn6Sn6},
author = {Nirmal J. Ghimire and Rebecca L. Dally and L. Poudel and D. C. Jones and D. Michel and N. Thapa Magar and M. Bleuel and Michael A. McGuire and J. S. Jiang and J. F. Mitchell and Jeffrey W. Lynn and I. I. Mazin},
doi = {10.1126/sciadv.abe2680},
issn = {2375-2548},
year = {2020},
date = {2020-12-01},
journal = {SCIENCE ADVANCES},
volume = {6},
number = {51},
publisher = {AMER ASSOC ADVANCEMENT SCIENCE},
address = {1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA},
abstract = {Identification, understanding, and manipulation of novel magnetic
textures are essential for the discovery of new quantum materials for
future spin-based electronic devices. In particular, materials that
manifest a large response to external stimuli such as a magnetic field
are subject to intense investigation. Here, we study the kagome-net
magnet YMn6Sn6 by magnetometry, transport, and neutron diffraction
measurements combined with first-principles calculations. We identify a
number of nontrivial magnetic phases, explain their microscopic nature,
and demonstrate that one of them hosts a large topological Hall effect
(THE). We propose a previously unidentified fluctuation-driven
mechanism, which leads to the THE at elevated temperatures. This
interesting physics comes from parametrically frustrated interplanar
exchange interactions that trigger strong magnetic fluctuations. Our
results pave a path to chiral spin textures, promising for novel
spintronics.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
textures are essential for the discovery of new quantum materials for
future spin-based electronic devices. In particular, materials that
manifest a large response to external stimuli such as a magnetic field
are subject to intense investigation. Here, we study the kagome-net
magnet YMn6Sn6 by magnetometry, transport, and neutron diffraction
measurements combined with first-principles calculations. We identify a
number of nontrivial magnetic phases, explain their microscopic nature,
and demonstrate that one of them hosts a large topological Hall effect
(THE). We propose a previously unidentified fluctuation-driven
mechanism, which leads to the THE at elevated temperatures. This
interesting physics comes from parametrically frustrated interplanar
exchange interactions that trigger strong magnetic fluctuations. Our
results pave a path to chiral spin textures, promising for novel
spintronics.
Choudhary, Kamal; Ansari, Jaafar N.; Mazin, Igor I.; Sauer, Karen L.
Density functional theory-based electric field gradient database Journal Article
In: SCIENTIFIC DATA, vol. 7, no. 1, 2020.
@article{WOS:000585253900004,
title = {Density functional theory-based electric field gradient database},
author = {Kamal Choudhary and Jaafar N. Ansari and Igor I. Mazin and Karen L. Sauer},
doi = {10.1038/s41597-020-00707-8},
year = {2020},
date = {2020-10-01},
journal = {SCIENTIFIC DATA},
volume = {7},
number = {1},
publisher = {NATURE RESEARCH},
address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY},
abstract = {The deviation of the electron density around the nuclei from spherical
symmetry determines the electric field gradient (EFG), which can be
measured by various types of spectroscopy. Nuclear Quadrupole Resonance
(NQR) is particularly sensitive to the EFG. The EFGs, and by implication
NQR frequencies, vary dramatically across materials. Consequently,
searching for NQR spectral lines in previously uninvestigated materials
represents a major challenge. Calculated EFGs can significantly aid at
the search's inception. To facilitate this task, we have applied
high-throughput density functional theory calculations to predict EFGs
for 15187 materials in the JARVIS-DFT database. This database, which
will include EFG as a standard entry, is continuously increasing. Given
the large scope of the database, it is impractical to verify each
calculation. However, we assess accuracy by singling out cases for which
reliable experimental information is readily available and compare them
to the calculations. We further present a statistical analysis of the
results. The database and tools associated with our work are made
publicly available by JARVIS-DFT (https://www.ctcms.nist.gov/similar to
knc6/JVASP.html) and NIST-JARVIS API (http://jarvis.nist.gov/).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
symmetry determines the electric field gradient (EFG), which can be
measured by various types of spectroscopy. Nuclear Quadrupole Resonance
(NQR) is particularly sensitive to the EFG. The EFGs, and by implication
NQR frequencies, vary dramatically across materials. Consequently,
searching for NQR spectral lines in previously uninvestigated materials
represents a major challenge. Calculated EFGs can significantly aid at
the search's inception. To facilitate this task, we have applied
high-throughput density functional theory calculations to predict EFGs
for 15187 materials in the JARVIS-DFT database. This database, which
will include EFG as a standard entry, is continuously increasing. Given
the large scope of the database, it is impractical to verify each
calculation. However, we assess accuracy by singling out cases for which
reliable experimental information is readily available and compare them
to the calculations. We further present a statistical analysis of the
results. The database and tools associated with our work are made
publicly available by JARVIS-DFT (https://www.ctcms.nist.gov/similar to
knc6/JVASP.html) and NIST-JARVIS API (http://jarvis.nist.gov/).
Wu, Liming; Xu, Jinxia; Li, Qiliang; Fan, Zhicheng; Mei, Fei; Zhou, Yuanming; Yan, Jiang; Chen, Ying
Enhanced performance of In(2)O(3)nanowire field effect transistors with controllable surface functionalization of Ag nanoparticles Journal Article
In: NANOTECHNOLOGY, vol. 31, no. 35, 2020, ISSN: 0957-4484.
@article{WOS:000542638200001,
title = {Enhanced performance of In(2)O(3)nanowire field effect transistors with
controllable surface functionalization of Ag nanoparticles},
author = {Liming Wu and Jinxia Xu and Qiliang Li and Zhicheng Fan and Fei Mei and Yuanming Zhou and Jiang Yan and Ying Chen},
doi = {10.1088/1361-6528/ab8f4a},
issn = {0957-4484},
year = {2020},
date = {2020-08-01},
journal = {NANOTECHNOLOGY},
volume = {31},
number = {35},
publisher = {IOP PUBLISHING LTD},
address = {TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND},
abstract = {Indium oxide (In2O3) nanowire field effect transistors (FETs) have great
potential in electronic and sensor applications owing to their suitable
band width and high electron mobility. However, the In(2)O(3)nanowire
FETs reported previously were operated in a depletion-mode, not suitable
to the integrated circuits result of the high-power consumption.
Therefore, tuning the electrical properties of In(2)O(3)nanowire FETs
into enhancement-mode is critical for the successful application in the
fields of high-performance electronics, optoelectronics and detectors.
In the work, a simple but effective strategy was carried out by
preparing Ag nanoparticle functionalized In(2)O(3)NWs to regulate the
threshold voltage (V-th) of In2O3NW FETs, successfully achieving
enhanced-mode devices. The threshold voltage can be regulated from -6.9
V to +7 V by controlling Ag density via deposition time. In addition,
the devices exhibited high performance: huge I-on/I(off)ratio > 10(8),
large maximum saturation current approximate to 800 mA and excellent
carrier mobility approximate to 129 cm(2)Vcs(-1). The enhanced
performance is attributed to the surface passivation by Ag nanoparticles
to reduce the density of traps and the charge transfer between traps and
the nanowires to regulate the V-th. The result indicates the application
of metal nanoparticles significantly improve oxide NW for low-power
FETs.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
potential in electronic and sensor applications owing to their suitable
band width and high electron mobility. However, the In(2)O(3)nanowire
FETs reported previously were operated in a depletion-mode, not suitable
to the integrated circuits result of the high-power consumption.
Therefore, tuning the electrical properties of In(2)O(3)nanowire FETs
into enhancement-mode is critical for the successful application in the
fields of high-performance electronics, optoelectronics and detectors.
In the work, a simple but effective strategy was carried out by
preparing Ag nanoparticle functionalized In(2)O(3)NWs to regulate the
threshold voltage (V-th) of In2O3NW FETs, successfully achieving
enhanced-mode devices. The threshold voltage can be regulated from -6.9
V to +7 V by controlling Ag density via deposition time. In addition,
the devices exhibited high performance: huge I-on/I(off)ratio > 10(8),
large maximum saturation current approximate to 800 mA and excellent
carrier mobility approximate to 129 cm(2)Vcs(-1). The enhanced
performance is attributed to the surface passivation by Ag nanoparticles
to reduce the density of traps and the charge transfer between traps and
the nanowires to regulate the V-th. The result indicates the application
of metal nanoparticles significantly improve oxide NW for low-power
FETs.
Keeling, Stephen; Nikolic, Predrag
Finite-momentum condensate brought on by a Zeeman field Journal Article
In: PHYSICAL REVIEW A, vol. 102, no. 6, 2020, ISSN: 2469-9926.
@article{WOS:000597804100005,
title = {Finite-momentum condensate brought on by a Zeeman field},
author = {Stephen Keeling and Predrag Nikolic},
doi = {10.1103/PhysRevA.102.063310},
issn = {2469-9926},
year = {2020},
date = {2020-12-01},
journal = {PHYSICAL REVIEW A},
volume = {102},
number = {6},
publisher = {AMER PHYSICAL SOC},
address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
abstract = {We study superfluid states in a two-dimensional fermionic attractive
Hubbard model with Zeeman coupling to an external field. Focusing our
attention on singlet pairing in both weak and strong coupling regimes,
we reveal a rich phase diagram of finite-momentum condensates which
exhibits both Fulde-Ferrell and Larkin-Ovchinnikov orders at zero
temperature. The latter are commensurate stripe states that
spontaneously break a lattice symmetry; many stable ordering wave
vectors are found as a function of particle density and a Zeeman field.
Stronger coupling significantly enhances the stability of the
finite-momentum condensates, but our numerical mean-field calculations
underestimate the effect of fluctuations and indicate a possible
localization near half filling.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Hubbard model with Zeeman coupling to an external field. Focusing our
attention on singlet pairing in both weak and strong coupling regimes,
we reveal a rich phase diagram of finite-momentum condensates which
exhibits both Fulde-Ferrell and Larkin-Ovchinnikov orders at zero
temperature. The latter are commensurate stripe states that
spontaneously break a lattice symmetry; many stable ordering wave
vectors are found as a function of particle density and a Zeeman field.
Stronger coupling significantly enhances the stability of the
finite-momentum condensates, but our numerical mean-field calculations
underestimate the effect of fluctuations and indicate a possible
localization near half filling.
Khan, Md Ashfaque Hossain; Thomson, Brian; Motayed, Abhishek; Li, Qiliang; Rao, Mulpuri V
Functionalization of GaN Nanowire Sensors With Metal Oxides: An Experimental and DFT Investigation Journal Article
In: IEEE SENSORS JOURNAL, vol. 20, no. 13, pp. 7138-7147, 2020, ISSN: 1530-437X.
@article{WOS:000543153400041,
title = {Functionalization of GaN Nanowire Sensors With Metal Oxides: An
Experimental and DFT Investigation},
author = {Md Ashfaque Hossain Khan and Brian Thomson and Abhishek Motayed and Qiliang Li and Mulpuri V Rao},
doi = {10.1109/JSEN.2020.2978221},
issn = {1530-437X},
year = {2020},
date = {2020-07-01},
journal = {IEEE SENSORS JOURNAL},
volume = {20},
number = {13},
pages = {7138-7147},
publisher = {IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC},
address = {445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA},
abstract = {The detection of NO2 molecules by GaN nanowire sensors which were
functionalized with various metal oxides have been comprehensively
studied with device fabrication, characterization and modeling with
first-principles calculations based on density functional theory (DFT).
In this work, GaN nanowires were prepared on Si substrate by standard
top-down fabrication process and then fabricated into resistor based
chemical sensors. The surface of GaN nanowires were functionalized by
three metal oxides: TiO2, ZnO and SnO2 for analysis. The UV illuminated
device characterization results indicated that the devices with TiO2
functionalization exhibited the highest response toward NO2 gas. It
showed quick response (240s) and recovery (280s) process with strong NO2
selectivity. In modeling, the oxide functionalized GaN in contact with
NO2 molecule was designed and geometrically optimized. Simulation
results indicated that TiO2 functionalization enabled the most energy
favorable surface for NO2 adsorption among the three metal oxides. In
addition, the electronic properties of these oxide functionalized GaN
have been studied in terms of the total density of states (TDOS) and
projected density of states (PDOS), indicating an excellent agreement
with the above-mentioned experimental measurements. Furthermore, the
effect of environmental humidity on the adsorbate-nanocomposite
interaction has been simulated and studied. Overall, the metal oxide
functionalization significantly enhances the performance of GaN gas
sensors and selecting an appropriate oxide will optimize the detection.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
functionalized with various metal oxides have been comprehensively
studied with device fabrication, characterization and modeling with
first-principles calculations based on density functional theory (DFT).
In this work, GaN nanowires were prepared on Si substrate by standard
top-down fabrication process and then fabricated into resistor based
chemical sensors. The surface of GaN nanowires were functionalized by
three metal oxides: TiO2, ZnO and SnO2 for analysis. The UV illuminated
device characterization results indicated that the devices with TiO2
functionalization exhibited the highest response toward NO2 gas. It
showed quick response (240s) and recovery (280s) process with strong NO2
selectivity. In modeling, the oxide functionalized GaN in contact with
NO2 molecule was designed and geometrically optimized. Simulation
results indicated that TiO2 functionalization enabled the most energy
favorable surface for NO2 adsorption among the three metal oxides. In
addition, the electronic properties of these oxide functionalized GaN
have been studied in terms of the total density of states (TDOS) and
projected density of states (PDOS), indicating an excellent agreement
with the above-mentioned experimental measurements. Furthermore, the
effect of environmental humidity on the adsorbate-nanocomposite
interaction has been simulated and studied. Overall, the metal oxide
functionalization significantly enhances the performance of GaN gas
sensors and selecting an appropriate oxide will optimize the detection.
Jo, Seong Soon; Singh, Akshay; Yang, Liqiu; Tiwari, Subodh C.; Hong, Sungwook; Krishnamoorthy, Aravind; Sales, Maria Gabriela; Oliver, Sean M.; Fox, Joshua; Cavalero, Randal L.; Snyder, David W.; Vora, Patrick M.; McDonnell, Stephen J.; Vashishta, Priya; Kalia, Rajiv K.; Nakano, Aiichiro; Jaramillo, R.
Growth Kinetics and Atomistic Mechanisms of Native Oxidation of ZrSxSe2-x and MoS2 Crystals Journal Article
In: NANO LETTERS, vol. 20, no. 12, pp. 8592-8599, 2020, ISSN: 1530-6984.
@article{WOS:000599507100026,
title = {Growth Kinetics and Atomistic Mechanisms of Native Oxidation of
ZrSxSe2-x and MoS2 Crystals},
author = {Seong Soon Jo and Akshay Singh and Liqiu Yang and Subodh C. Tiwari and Sungwook Hong and Aravind Krishnamoorthy and Maria Gabriela Sales and Sean M. Oliver and Joshua Fox and Randal L. Cavalero and David W. Snyder and Patrick M. Vora and Stephen J. McDonnell and Priya Vashishta and Rajiv K. Kalia and Aiichiro Nakano and R. Jaramillo},
doi = {10.1021/acs.nanolett.0c03263},
issn = {1530-6984},
year = {2020},
date = {2020-12-01},
journal = {NANO LETTERS},
volume = {20},
number = {12},
pages = {8592-8599},
publisher = {AMER CHEMICAL SOC},
address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA},
abstract = {A thorough understanding of native oxides is essential for designing
semiconductor devices. Here, we report a study of the rate and
mechanisms of spontaneous oxidation of bulk single crystals of ZrSxSe2-x
alloys and MoS2. ZrSxSe2-x alloys oxidize rapidly, and the oxidation
rate increases with Se content. Oxidation of basal surfaces is initiated
by favorable O-2 adsorption and proceeds by a mechanism of Zr-O bond
switching, that collapses the van der Waals gaps, and is facilitated by
progressive redox transitions of the chalcogen. The rate-limiting
process is the formation and out-diffusion of SO2. In contrast, MoS2
basal surfaces are stable due to unfavorable oxygen adsorption. Our
results provide insight and quantitative guidance for designing and
processing semiconductor devices based on ZrSxSe2-x and MoS2 and
identify the atomistic-scale mechanisms of bonding and phase
transformations in layered materials with competing anions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
semiconductor devices. Here, we report a study of the rate and
mechanisms of spontaneous oxidation of bulk single crystals of ZrSxSe2-x
alloys and MoS2. ZrSxSe2-x alloys oxidize rapidly, and the oxidation
rate increases with Se content. Oxidation of basal surfaces is initiated
by favorable O-2 adsorption and proceeds by a mechanism of Zr-O bond
switching, that collapses the van der Waals gaps, and is facilitated by
progressive redox transitions of the chalcogen. The rate-limiting
process is the formation and out-diffusion of SO2. In contrast, MoS2
basal surfaces are stable due to unfavorable oxygen adsorption. Our
results provide insight and quantitative guidance for designing and
processing semiconductor devices based on ZrSxSe2-x and MoS2 and
identify the atomistic-scale mechanisms of bonding and phase
transformations in layered materials with competing anions.
Wickramaratne, Darshana; Khmelevskyi, Sergii; Agterberg, Daniel F.; Mazin, I. I.
Ising Superconductivity and Magnetism in NbSe2 Journal Article
In: PHYSICAL REVIEW X, vol. 10, no. 4, 2020, ISSN: 2160-3308.
@article{WOS:000575037700001,
title = {Ising Superconductivity and Magnetism in NbSe2},
author = {Darshana Wickramaratne and Sergii Khmelevskyi and Daniel F. Agterberg and I. I. Mazin},
doi = {10.1103/PhysRevX.10.041003},
issn = {2160-3308},
year = {2020},
date = {2020-10-01},
journal = {PHYSICAL REVIEW X},
volume = {10},
number = {4},
publisher = {AMER PHYSICAL SOC},
address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
abstract = {Recent studies on superconductivity in NbSe2 have demonstrated a large
anisotropy in the superconducting critical field when the material is
reduced to a single monolayer. Motivated by this recent discovery, we
use density-functional theory (DFT) calculations to quantitatively
address the superconducting properties of bulk and monolayer NbSe2. We
demonstrate that NbSe2 is close to a ferromagnetic instability, and
analyze our results in the context of experimental measurements of the
spin susceptibility in NbSe2. We show how this magnetic instability,
which is pronounced in a single monolayer, can enable sizable
singlet-triplet mixing of the superconducting order parameter, contrary
to contemporary considerations of the pairing symmetry in monolayer
NbSe2, and discuss approaches as to how this degree of mixing can be
addressed quantitatively within our DFT framework. Our calculations also
enable a quantitative description of the large anisotropy of the
superconducting critical field, using DFT calculations of monolayer
NbSe2 in the normal state.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
anisotropy in the superconducting critical field when the material is
reduced to a single monolayer. Motivated by this recent discovery, we
use density-functional theory (DFT) calculations to quantitatively
address the superconducting properties of bulk and monolayer NbSe2. We
demonstrate that NbSe2 is close to a ferromagnetic instability, and
analyze our results in the context of experimental measurements of the
spin susceptibility in NbSe2. We show how this magnetic instability,
which is pronounced in a single monolayer, can enable sizable
singlet-triplet mixing of the superconducting order parameter, contrary
to contemporary considerations of the pairing symmetry in monolayer
NbSe2, and discuss approaches as to how this degree of mixing can be
addressed quantitatively within our DFT framework. Our calculations also
enable a quantitative description of the large anisotropy of the
superconducting critical field, using DFT calculations of monolayer
NbSe2 in the normal state.
Kim, Minsu; Yang, Kwansoo; Kim, Yong Seok; Won, Jong Chan; Kang, Pilgyu; Kim, Yun Ho; Kim, Byoung Gak
Laser-induced photothermal generation of flexible and salt-resistant monolithic bilayer membranes for efficient solar desalination Journal Article
In: CARBON, vol. 164, pp. 349-356, 2020, ISSN: 0008-6223.
@article{WOS:000536478700006,
title = {Laser-induced photothermal generation of flexible and salt-resistant
monolithic bilayer membranes for efficient solar desalination},
author = {Minsu Kim and Kwansoo Yang and Yong Seok Kim and Jong Chan Won and Pilgyu Kang and Yun Ho Kim and Byoung Gak Kim},
doi = {10.1016/j.carbon.2020.03.059},
issn = {0008-6223},
year = {2020},
date = {2020-08-01},
journal = {CARBON},
volume = {164},
pages = {349-356},
publisher = {PERGAMON-ELSEVIER SCIENCE LTD},
address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND},
abstract = {Harvesting solar energy and generating steam through solar thermal
energy are viable approaches with diverse applications such as power
generation, desalination, and water purification. Particularly, for
efficient and stable solar desalination, hierarchically porous materials
are desired to enable the required multiple functionalities. However,
high thermal/chemical energy required and time consumed remain
roadblocks. In this study, a facile, fast, and scalable laser-induced
photothermal method to achieve flexible monolithic bilayer sheets (MBS)
of hierarchically porous graphitic carbon (HPGC) and polymeric foam for
use in salt-resistant and flexible solar steam generators is reported.
The MBS-based self-floating solar steam generator shows outstanding
solar desalination performance with a solar thermal efficiency of 83.2%
(1-sun) and a high salt-rejection ratio (99.9%). Efficient solar
thermal energy transformation is achieved by the versatile
multi-functionalities of the MBS, including broad-spectrum solar light
absorption, heat localization, and capillary action. Anisotropic wetting
properties of hydrophobic HPGC and hydrophilic polyimide (PI) foam
effectively prevent salt accumulation on the HPGC surface. The
salt-resistant MBS enable long-term stability for solar desalination
with actual seawater. Our laser-based photothermal method has potential
in the development of high-performance solar thermal systems with
substantial cost reduction by scalable production of multiscale
hierarchically structured materials from micro-structured polymers. (C)
2020 Elsevier Ltd. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
energy are viable approaches with diverse applications such as power
generation, desalination, and water purification. Particularly, for
efficient and stable solar desalination, hierarchically porous materials
are desired to enable the required multiple functionalities. However,
high thermal/chemical energy required and time consumed remain
roadblocks. In this study, a facile, fast, and scalable laser-induced
photothermal method to achieve flexible monolithic bilayer sheets (MBS)
of hierarchically porous graphitic carbon (HPGC) and polymeric foam for
use in salt-resistant and flexible solar steam generators is reported.
The MBS-based self-floating solar steam generator shows outstanding
solar desalination performance with a solar thermal efficiency of 83.2%
(1-sun) and a high salt-rejection ratio (99.9%). Efficient solar
thermal energy transformation is achieved by the versatile
multi-functionalities of the MBS, including broad-spectrum solar light
absorption, heat localization, and capillary action. Anisotropic wetting
properties of hydrophobic HPGC and hydrophilic polyimide (PI) foam
effectively prevent salt accumulation on the HPGC surface. The
salt-resistant MBS enable long-term stability for solar desalination
with actual seawater. Our laser-based photothermal method has potential
in the development of high-performance solar thermal systems with
substantial cost reduction by scalable production of multiscale
hierarchically structured materials from micro-structured polymers. (C)
2020 Elsevier Ltd. All rights reserved.
Joshi, Jaydeep; Zhou, Tong; Krylyuk, Sergiy; Davydov, Albert V.; Zutic, Igor; Vora, Patrick M.
Localized Excitons in NbSe2-MoSe2 Heterostructures Journal Article
In: ACS NANO, vol. 14, no. 7, pp. 8528-8538, 2020, ISSN: 1936-0851.
@article{WOS:000557762800074,
title = {Localized Excitons in NbSe2-MoSe2 Heterostructures},
author = {Jaydeep Joshi and Tong Zhou and Sergiy Krylyuk and Albert V. Davydov and Igor Zutic and Patrick M. Vora},
doi = {10.1021/acsnano.0c02803},
issn = {1936-0851},
year = {2020},
date = {2020-07-01},
journal = {ACS NANO},
volume = {14},
number = {7},
pages = {8528-8538},
publisher = {AMER CHEMICAL SOC},
address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA},
abstract = {Neutral and charged excitons (trions) in atomically thin materials offer
important capabilities for photonics, from ultrafast photodetectors to
highly efficient light-emitting diodes and lasers. Recent studies of van
der Waals (vdW) heterostructures comprised of dissimilar monolayer
materials have uncovered a wealth of optical phenomena that are
predominantly governed by interlayer interactions. Here, we examine the
optical properties in NbSe2-MoSe2 vdW heterostructures, which provide an
important model system to study metal-semiconductor interfaces, a common
element in optoelectronics. Through low-temperature photoluminescence
(PL) microscopy, we discover a sharp emission feature, L1, that is
localized at the NbSe2-capped regions of MoSe2. L1 is observed at
energies below the commonly studied MoSe2 excitons and trions and
exhibits temperature- and power-dependent PL consistent with exciton
localization in a confining potential. This PL feature is robust,
observed in a variety of samples fabricated with different stacking
geometries and cleaning procedures. Using first-principles calculations,
we reveal that the confinement potential required for exciton
localization naturally arises from the in-plane band bending due to the
changes in the electron affinity between pristine MoSe2 and NbSe2-MoSe2
heterostructure. We discuss the implications of our studies for
atomically thin optoelectronics devices with atomically sharp interfaces
and tunable electronic structures.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
important capabilities for photonics, from ultrafast photodetectors to
highly efficient light-emitting diodes and lasers. Recent studies of van
der Waals (vdW) heterostructures comprised of dissimilar monolayer
materials have uncovered a wealth of optical phenomena that are
predominantly governed by interlayer interactions. Here, we examine the
optical properties in NbSe2-MoSe2 vdW heterostructures, which provide an
important model system to study metal-semiconductor interfaces, a common
element in optoelectronics. Through low-temperature photoluminescence
(PL) microscopy, we discover a sharp emission feature, L1, that is
localized at the NbSe2-capped regions of MoSe2. L1 is observed at
energies below the commonly studied MoSe2 excitons and trions and
exhibits temperature- and power-dependent PL consistent with exciton
localization in a confining potential. This PL feature is robust,
observed in a variety of samples fabricated with different stacking
geometries and cleaning procedures. Using first-principles calculations,
we reveal that the confinement potential required for exciton
localization naturally arises from the in-plane band bending due to the
changes in the electron affinity between pristine MoSe2 and NbSe2-MoSe2
heterostructure. We discuss the implications of our studies for
atomically thin optoelectronics devices with atomically sharp interfaces
and tunable electronic structures.
Fuhrman, W. T.; Nikolic, P.
Magnetic impurities in Kondo insulators: An application to samarium hexaboride Journal Article
In: PHYSICAL REVIEW B, vol. 101, no. 24, 2020, ISSN: 2469-9950.
@article{WOS:000537315300006,
title = {Magnetic impurities in Kondo insulators: An application to samarium
hexaboride},
author = {W. T. Fuhrman and P. Nikolic},
doi = {10.1103/PhysRevB.101.245118},
issn = {2469-9950},
year = {2020},
date = {2020-06-01},
journal = {PHYSICAL REVIEW B},
volume = {101},
number = {24},
publisher = {AMER PHYSICAL SOC},
address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
abstract = {Impurities and defects in Kondo insulators can have an unusual impact on
dynamics that blends with effects of intrinsic electron correlations.
Such crystal imperfections are difficult to avoid, and their
consequences are incompletely understood. Here we study magnetic
impurities in Kondo insulators via perturbation theory of the s-d Kondo
impurity model adapted to small-band-gap insulators. The calculated
magnetization and specific heat agree with recent thermodynamic
measurements in samarium hexaboride (SmB6). This qualitative agreement
supports the physical picture of multichannel Kondo screening of local
moments by electrons and holes involving both intrinsic and impurity
bands. Specific heat is thermally activated in zero field by Kondo
screening through subgap impurity bands and exhibits a characteristic
upturn as the temperature is decreased. In contrast, magnetization
obtains a dominant quantum correction from partial screening by virtual
particle-hole pairs in intrinsic bands. We point out that magnetic
impurities could impact de Haas-van Alphen quantum oscillations in SmB6,
through the effects of Landau quantization in intrinsic bands on the
Kondo screening of impurity moments.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
dynamics that blends with effects of intrinsic electron correlations.
Such crystal imperfections are difficult to avoid, and their
consequences are incompletely understood. Here we study magnetic
impurities in Kondo insulators via perturbation theory of the s-d Kondo
impurity model adapted to small-band-gap insulators. The calculated
magnetization and specific heat agree with recent thermodynamic
measurements in samarium hexaboride (SmB6). This qualitative agreement
supports the physical picture of multichannel Kondo screening of local
moments by electrons and holes involving both intrinsic and impurity
bands. Specific heat is thermally activated in zero field by Kondo
screening through subgap impurity bands and exhibits a characteristic
upturn as the temperature is decreased. In contrast, magnetization
obtains a dominant quantum correction from partial screening by virtual
particle-hole pairs in intrinsic bands. We point out that magnetic
impurities could impact de Haas-van Alphen quantum oscillations in SmB6,
through the effects of Landau quantization in intrinsic bands on the
Kondo screening of impurity moments.
Yuan, Haiwen; Xiao, Changshi; Wang, Yanfeng; Peng, Xin; Wen, Yuanqiao; Li, Qiliang
Maritime vessel emission monitoring by an UAV gas sensor system Journal Article
In: OCEAN ENGINEERING, vol. 218, 2020, ISSN: 0029-8018.
@article{WOS:000598977600071,
title = {Maritime vessel emission monitoring by an UAV gas sensor system},
author = {Haiwen Yuan and Changshi Xiao and Yanfeng Wang and Xin Peng and Yuanqiao Wen and Qiliang Li},
doi = {10.1016/j.oceaneng.2020.108206},
issn = {0029-8018},
year = {2020},
date = {2020-12-01},
journal = {OCEAN ENGINEERING},
volume = {218},
publisher = {PERGAMON-ELSEVIER SCIENCE LTD},
address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND},
abstract = {Monitoring the gas emission of maritime vessels is very challenging as
the fields are almost inaccessible and the emission is very susceptible
to the surrounding environment. In ultra-large-scale maritime scenes,
mobile robots capable of gas detection and tracking will most likely
fall into atmospheric turbulence. In this work, an enhanced tracking
algorithm using our unmanned aerial vehicle (UAV) gas sensor system is
proposed for maritime vessel emission monitoring. A global prediction is
acquired by modelling the emission of individual vessel, while another
local gradient direction can be calculated from the real-time onboard
sensor measurements. By a probabilistic framework, the global prediction
and the gradient detection are fused to generate a more reliable
navigation for the UAV. In order to verify the proposed algorithm, real
monitoring experiments using the developed UAV gas sensor system are
presented and SO2, NOx contents in vessel emissions are conducted. A
comparison between the UAV-based detections and the off-line sampled
data is preformed, and the results indicate that the proposed algorithm
has the advantage in exactly guiding the UAV towards the vessel
emission.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
the fields are almost inaccessible and the emission is very susceptible
to the surrounding environment. In ultra-large-scale maritime scenes,
mobile robots capable of gas detection and tracking will most likely
fall into atmospheric turbulence. In this work, an enhanced tracking
algorithm using our unmanned aerial vehicle (UAV) gas sensor system is
proposed for maritime vessel emission monitoring. A global prediction is
acquired by modelling the emission of individual vessel, while another
local gradient direction can be calculated from the real-time onboard
sensor measurements. By a probabilistic framework, the global prediction
and the gradient detection are fused to generate a more reliable
navigation for the UAV. In order to verify the proposed algorithm, real
monitoring experiments using the developed UAV gas sensor system are
presented and SO2, NOx contents in vessel emissions are conducted. A
comparison between the UAV-based detections and the off-line sampled
data is preformed, and the results indicate that the proposed algorithm
has the advantage in exactly guiding the UAV towards the vessel
emission.
Ye, Huixian; Shi, Chen; Li, Jiang; Tian, Li; Zeng, Min; Wang, Hui; Li, Qiliang
New Alternating Current Noise Analytics Enables High Discrimination in Gas Sensing Journal Article
In: ANALYTICAL CHEMISTRY, vol. 92, no. 1, pp. 824-829, 2020, ISSN: 0003-2700.
@article{ISI:000506719400071,
title = {New Alternating Current Noise Analytics Enables High Discrimination in
Gas Sensing},
author = {Huixian Ye and Chen Shi and Jiang Li and Li Tian and Min Zeng and Hui Wang and Qiliang Li},
doi = {10.1021/acs.analchem.9b03312},
issn = {0003-2700},
year = {2020},
date = {2020-01-01},
journal = {ANALYTICAL CHEMISTRY},
volume = {92},
number = {1},
pages = {824-829},
publisher = {AMER CHEMICAL SOC},
address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA},
abstract = {Feature analysis has been increasingly considered as an important way to
enhance the discrimination performance of gas sensors. In this work, a
new analytical method based on alternating current noise spectrum is
developed to discriminate chemically and structurally similar gases with
remarkable performance. Compared with the conventional analytics based
on the maximum, integral, and time of response, the noise spectrum of
electrical response introduces a new informative feature to discriminate
chemical gases. In experiment, three chemically and structurally similar
gases, mesitylene, toluene, and o-xylene, are tested on ZnO thin film
gas sensors. The result indicated that the noise analytics assisted by
the support vector machine algorithm discriminated these similar gases
with 94.2% in precision, about 20% higher than those alternating
current noise analytics is very promising for application in
sensorsobtained by conventional methods. Such a new for high
discrimination precision.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
enhance the discrimination performance of gas sensors. In this work, a
new analytical method based on alternating current noise spectrum is
developed to discriminate chemically and structurally similar gases with
remarkable performance. Compared with the conventional analytics based
on the maximum, integral, and time of response, the noise spectrum of
electrical response introduces a new informative feature to discriminate
chemical gases. In experiment, three chemically and structurally similar
gases, mesitylene, toluene, and o-xylene, are tested on ZnO thin film
gas sensors. The result indicated that the noise analytics assisted by
the support vector machine algorithm discriminated these similar gases
with 94.2% in precision, about 20% higher than those alternating
current noise analytics is very promising for application in
sensorsobtained by conventional methods. Such a new for high
discrimination precision.
Nikolic, Predrag
Quantum field theory of topological spin dynamics Journal Article
In: PHYSICAL REVIEW B, vol. 102, no. 7, 2020, ISSN: 2469-9950.
@article{WOS:000560962500003,
title = {Quantum field theory of topological spin dynamics},
author = {Predrag Nikolic},
doi = {10.1103/PhysRevB.102.075131},
issn = {2469-9950},
year = {2020},
date = {2020-08-01},
journal = {PHYSICAL REVIEW B},
volume = {102},
number = {7},
publisher = {AMER PHYSICAL SOC},
address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
abstract = {We develop a field theory of quantum magnets and magnetic (semi)metals,
which is suitable for the analysis of their universal and topological
properties. The systems of interest include collinear, coplanar, and
general noncoplanar magnets. At the basic level, we describe the
dynamics of magnetic moments using smooth vector fields in the continuum
limit. Dzyaloshinskii-Moriya interaction is captured by a non-Abelian
vector gauge field, and chiral spin couplings related to topological
defects appear as higher-rank antisymmetric tensor gauge fields. We
distinguish type-I and type-II magnets by their equilibrium response to
the non-Abelian gauge flux, and characterize the resulting lattices of
skyrmions and hedgehogs, the spectra of spin waves, and the chiral
response to external perturbations. The general spin-orbit coupling of
electrons is similarly described by non-Abelian gauge fields, including
higher-rank tensors related to the electronic Berry flux. Itinerant
electrons and local moments exchange their gauge fluxes through Kondo
and Hund interactions. Hence, by utilizing gauge fields, this theory
provides a unifying physical picture of ``intrinsic'' and
``topological'' anomalous Hall effects, spin-Hall effects, and other
correlations between the topological properties of electrons and
moments. We predict ``topological'' magnetoelectric effect in
materials prone to hosting hedgehogs. Links to experiments and model
calculations are provided by deriving the couplings and gauge fields
from generic microscopic models, including the Hubbard model with
spin-orbit interactions. Much of the formal analysis is generalized to d
spatial dimensions in order to access the pi(d-1)(Sd-1) homotopy
classification of the magnetic hedgehog topological defects, and
establish the possibility of novel quantum spin liquids that exhibit a
fractional magnetoelectric effect. However, we emphasize the form of all results in the physically relevant d = 3 dimensions, and discuss a few
applications to topological magnetic conductors like Mn3Sn and Pr2Ir2O7.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
which is suitable for the analysis of their universal and topological
properties. The systems of interest include collinear, coplanar, and
general noncoplanar magnets. At the basic level, we describe the
dynamics of magnetic moments using smooth vector fields in the continuum
limit. Dzyaloshinskii-Moriya interaction is captured by a non-Abelian
vector gauge field, and chiral spin couplings related to topological
defects appear as higher-rank antisymmetric tensor gauge fields. We
distinguish type-I and type-II magnets by their equilibrium response to
the non-Abelian gauge flux, and characterize the resulting lattices of
skyrmions and hedgehogs, the spectra of spin waves, and the chiral
response to external perturbations. The general spin-orbit coupling of
electrons is similarly described by non-Abelian gauge fields, including
higher-rank tensors related to the electronic Berry flux. Itinerant
electrons and local moments exchange their gauge fluxes through Kondo
and Hund interactions. Hence, by utilizing gauge fields, this theory
provides a unifying physical picture of ``intrinsic'' and
``topological'' anomalous Hall effects, spin-Hall effects, and other
correlations between the topological properties of electrons and
moments. We predict ``topological'' magnetoelectric effect in
materials prone to hosting hedgehogs. Links to experiments and model
calculations are provided by deriving the couplings and gauge fields
from generic microscopic models, including the Hubbard model with
spin-orbit interactions. Much of the formal analysis is generalized to d
spatial dimensions in order to access the pi(d-1)(Sd-1) homotopy
classification of the magnetic hedgehog topological defects, and
establish the possibility of novel quantum spin liquids that exhibit a
fractional magnetoelectric effect. However, we emphasize the form of all results in the physically relevant d = 3 dimensions, and discuss a few
applications to topological magnetic conductors like Mn3Sn and Pr2Ir2O7.
Qin, Kaiqiang; Huang, Jinghao; Holguin, Kathryn; Luo, Chao
Recent advances in developing organic electrode materials for multivalent rechargeable batteries Journal Article
In: ENERGY & ENVIRONMENTAL SCIENCE, vol. 13, no. 11, pp. 3950-3992, 2020, ISSN: 1754-5692.
@article{WOS:000589801000007,
title = {Recent advances in developing organic electrode materials for
multivalent rechargeable batteries},
author = {Kaiqiang Qin and Jinghao Huang and Kathryn Holguin and Chao Luo},
doi = {10.1039/d0ee02111c},
issn = {1754-5692},
year = {2020},
date = {2020-11-01},
journal = {ENERGY \& ENVIRONMENTAL SCIENCE},
volume = {13},
number = {11},
pages = {3950-3992},
publisher = {ROYAL SOC CHEMISTRY},
address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS,
ENGLAND},
abstract = {Due to the low cost and abundance of multivalent metallic resources
(Mg/Al/Zn/Ca), multivalent rechargeable batteries (MRBs) are promising
alternatives to Li-ion and Pb-acid batteries for grid-scale stationary
energy storage applications. However, the high performance of inorganic
electrode materials in Li-ion batteries does not extend to MRBs, because
the high charge density of multivalent cations dramatically reduces
their diffusivity in the crystal lattice of inorganic materials. To
achieve high-performance MRBs, organic electrode materials (OEMs) with
abundant structural diversity and high structural tunability offer
opportunities. This review presents an overview of the state-of-the-art
OEMs in MRBs, including non-aqueous rechargeable Mg/Al/Zn and aqueous
rechargeable Mg/Al/Zn/Ca batteries. The advantages, challenges,
development, mechanism, structure, and performance of OEMs in MRBs are
discussed in detail. To provide a comprehensive and thorough
understanding of OEMs in MRBs, the correlation between molecular
structure and electrochemical behavior is also summarized and discussed.
This review offers insights for the rational structure design and
performance optimization of advanced OEMs in MRBs.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
(Mg/Al/Zn/Ca), multivalent rechargeable batteries (MRBs) are promising
alternatives to Li-ion and Pb-acid batteries for grid-scale stationary
energy storage applications. However, the high performance of inorganic
electrode materials in Li-ion batteries does not extend to MRBs, because
the high charge density of multivalent cations dramatically reduces
their diffusivity in the crystal lattice of inorganic materials. To
achieve high-performance MRBs, organic electrode materials (OEMs) with
abundant structural diversity and high structural tunability offer
opportunities. This review presents an overview of the state-of-the-art
OEMs in MRBs, including non-aqueous rechargeable Mg/Al/Zn and aqueous
rechargeable Mg/Al/Zn/Ca batteries. The advantages, challenges,
development, mechanism, structure, and performance of OEMs in MRBs are
discussed in detail. To provide a comprehensive and thorough
understanding of OEMs in MRBs, the correlation between molecular
structure and electrochemical behavior is also summarized and discussed.
This review offers insights for the rational structure design and
performance optimization of advanced OEMs in MRBs.
Petsch, A. N.; Zhu, M.; Enderle, Mechthild; Mao, Z. Q.; Maeno, Y.; Mazin, I. I.; Hayden, S. M.
Reduction of the Spin Susceptibility in the Superconducting State of Sr2RuO4 Observed by Polarized Neutron Scattering Journal Article
In: PHYSICAL REVIEW LETTERS, vol. 125, no. 21, 2020, ISSN: 0031-9007.
@article{WOS:000590411700008,
title = {Reduction of the Spin Susceptibility in the Superconducting State of
Sr2RuO4 Observed by Polarized Neutron Scattering},
author = {A. N. Petsch and M. Zhu and Mechthild Enderle and Z. Q. Mao and Y. Maeno and I. I. Mazin and S. M. Hayden},
doi = {10.1103/PhysRevLett.125.217004},
issn = {0031-9007},
year = {2020},
date = {2020-11-01},
journal = {PHYSICAL REVIEW LETTERS},
volume = {125},
number = {21},
publisher = {AMER PHYSICAL SOC},
address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
abstract = {Recent observations [A. Pustogow et al., Nature (London) 574, 72
(2019).] of a drop of the O-17 nuclear magnetic resonance (NMR) Knight
shift in the superconducting state of Sr2RuO4 challenged the popular
picture of a chiral odd-parity paired state in this compound. Here we
use polarized neutron scattering (PNS) to show that there is a 34 +/-
6% drop in the magnetic susceptibility at the Ru site below the
superconducting transition temperature. We measure at lower fields H
similar to( )1/3 H-c2 than a previous PNS study allowing the suppression
to be observed. The PNS measurements show a smaller susceptibility
suppression than NMR measurements performed at similar field and temperature. Our results rule out the chiral odd-parity d = (z) over cap
(k(x) +/- ik(y)) state and are consistent with several recent proposals
for the order parameter including even-parity B-1g and odd-parity
helical states.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
(2019).] of a drop of the O-17 nuclear magnetic resonance (NMR) Knight
shift in the superconducting state of Sr2RuO4 challenged the popular
picture of a chiral odd-parity paired state in this compound. Here we
use polarized neutron scattering (PNS) to show that there is a 34 +/-
6% drop in the magnetic susceptibility at the Ru site below the
superconducting transition temperature. We measure at lower fields H
similar to( )1/3 H-c2 than a previous PNS study allowing the suppression
to be observed. The PNS measurements show a smaller susceptibility
suppression than NMR measurements performed at similar field and temperature. Our results rule out the chiral odd-parity d = (z) over cap
(k(x) +/- ik(y)) state and are consistent with several recent proposals
for the order parameter including even-parity B-1g and odd-parity
helical states.
Maiwald, Jannis; Mazin, Igor I.; Gurevich, Alex; Aronson, Meigan
Superconductivity in La2Ni2In Journal Article
In: PHYSICAL REVIEW B, vol. 102, no. 16, 2020, ISSN: 2469-9950.
@article{WOS:000577073300002,
title = {Superconductivity in La2Ni2In},
author = {Jannis Maiwald and Igor I. Mazin and Alex Gurevich and Meigan Aronson},
doi = {10.1103/PhysRevB.102.165125},
issn = {2469-9950},
year = {2020},
date = {2020-10-01},
journal = {PHYSICAL REVIEW B},
volume = {102},
number = {16},
publisher = {AMER PHYSICAL SOC},
address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
abstract = {We report here the properties of single crystals of La2Ni2In. Electrical
resistivity and specific heat measurements concur with the results of
density functional theory calculations, finding that La2Ni2In is a
weakly correlated metal, where the Ni magnetism is almost completely
quenched, leaving only a weak Stoner enhancement of the density of
states. Superconductivity is observed at temperatures below 0.9 K. A
detailed analysis of the field and temperature dependencies of the
resistivity, magnetic susceptibility, and specific heat at the lowest
temperatures reveals that La2Ni2In is a dirty type-II superconductor
with likely s-wave gap symmetry. Nanoclusters of ferromagnetic
inclusions significantly affect the subgap states resulting in a
nonexponential temperature dependence of the specific heat C(T) at T <<
T-c.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
resistivity and specific heat measurements concur with the results of
density functional theory calculations, finding that La2Ni2In is a
weakly correlated metal, where the Ni magnetism is almost completely
quenched, leaving only a weak Stoner enhancement of the density of
states. Superconductivity is observed at temperatures below 0.9 K. A
detailed analysis of the field and temperature dependencies of the
resistivity, magnetic susceptibility, and specific heat at the lowest
temperatures reveals that La2Ni2In is a dirty type-II superconductor
with likely s-wave gap symmetry. Nanoclusters of ferromagnetic
inclusions significantly affect the subgap states resulting in a
nonexponential temperature dependence of the specific heat C(T) at T <<
T-c.
Ghimire, Nirmal J; Mazin, Igor I
Topology and correlations on the kagome lattice Journal Article
In: NATURE MATERIALS, vol. 19, no. 2, pp. 137-138, 2020, ISSN: 1476-1122.
@article{ISI:000511169400007,
title = {Topology and correlations on the kagome lattice},
author = {Nirmal J Ghimire and Igor I Mazin},
doi = {10.1038/s41563-019-0589-8},
issn = {1476-1122},
year = {2020},
date = {2020-02-01},
journal = {NATURE MATERIALS},
volume = {19},
number = {2},
pages = {137-138},
publisher = {NATURE PUBLISHING GROUP},
address = {MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND},
abstract = {Both a Dirac band and a flat band - signatures of topology and
correlation - are found in a prototypical antiferromagnetic kagome
lattice compound FeSn.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
correlation - are found in a prototypical antiferromagnetic kagome
lattice compound FeSn.
Walkup, Daniel; Ghahari, Fereshte; Gutierrez, Christopher; Watanabe, Kenji; Taniguchi, Takashi; Zhitenev, Nikolai B; Stroscio, Joseph A
Tuning single-electron charging and interactions between compressible Landau level islands in graphene Journal Article
In: PHYSICAL REVIEW B, vol. 101, no. 3, 2020, ISSN: 2469-9950.
@article{ISI:000510146500006,
title = {Tuning single-electron charging and interactions between compressible
Landau level islands in graphene},
author = {Daniel Walkup and Fereshte Ghahari and Christopher Gutierrez and Kenji Watanabe and Takashi Taniguchi and Nikolai B Zhitenev and Joseph A Stroscio},
doi = {10.1103/PhysRevB.101.035428},
issn = {2469-9950},
year = {2020},
date = {2020-01-01},
journal = {PHYSICAL REVIEW B},
volume = {101},
number = {3},
publisher = {AMER PHYSICAL SOC},
address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
abstract = {Interacting and tunable quantum dots (QDs) have been extensively
exploited in condensed matter physics and quantum information science.
Using a low-temperature scanning tunneling microscope (STM), we both
create and directly image a new type of coupled QD system in graphene, a
highly interacting quantum relativistic system with tunable density.
Using detailed scanning tunneling spectroscopy (STS) measurements, we
show that Landau quantization inside a potential well enables novel
electron confinement via the incompressible strips between partially
filled Landau levels (LLs), forming isolated and concentric LL QDs. By
changing the charge density and the magnetic field we can tune
continuously between single- and double-concentric LL QD systems within
the same potential well. In the concentric QD regime, single-electron
charging peaks of the two dots intersect, displaying a characteristic
avoidance pattern. At moderate fields, we observe an unconventional
avoidance pattern that differs significantly from that observed in
capacitively coupled double-QD systems. We find that we can reproduce in
detail this anomalous avoidance pattern within the framework of the
electrostatic double-QD model by replacing the capacitive interdot
coupling with a phenomenological charge-counting system in which charges
in the inner concentric dot are counted in the total charge of both
islands. The emergence of such strange forms of interdot coupling in a
single potential well, together with the ease of producing such charge
pockets in graphene and other two-dimensional (2D) materials, reveals an
intriguing testbed for the confinement of 2D electrons in customizable
potentials.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
exploited in condensed matter physics and quantum information science.
Using a low-temperature scanning tunneling microscope (STM), we both
create and directly image a new type of coupled QD system in graphene, a
highly interacting quantum relativistic system with tunable density.
Using detailed scanning tunneling spectroscopy (STS) measurements, we
show that Landau quantization inside a potential well enables novel
electron confinement via the incompressible strips between partially
filled Landau levels (LLs), forming isolated and concentric LL QDs. By
changing the charge density and the magnetic field we can tune
continuously between single- and double-concentric LL QD systems within
the same potential well. In the concentric QD regime, single-electron
charging peaks of the two dots intersect, displaying a characteristic
avoidance pattern. At moderate fields, we observe an unconventional
avoidance pattern that differs significantly from that observed in
capacitively coupled double-QD systems. We find that we can reproduce in
detail this anomalous avoidance pattern within the framework of the
electrostatic double-QD model by replacing the capacitive interdot
coupling with a phenomenological charge-counting system in which charges
in the inner concentric dot are counted in the total charge of both
islands. The emergence of such strange forms of interdot coupling in a
single potential well, together with the ease of producing such charge
pockets in graphene and other two-dimensional (2D) materials, reveals an
intriguing testbed for the confinement of 2D electrons in customizable
potentials.
Anikin, A.; Schaller, R. D.; Wiederrecht, G. P.; Margine, E. R.; Mazin, I. I.; Karapetrov, G.
Ultrafast dynamics in the high-symmetry and in the charge density wave phase of 2H-NbSe2 Journal Article
In: PHYSICAL REVIEW B, vol. 102, no. 20, 2020, ISSN: 2469-9950.
@article{WOS:000594089300010,
title = {Ultrafast dynamics in the high-symmetry and in the charge density wave
phase of 2H-NbSe2},
author = {A. Anikin and R. D. Schaller and G. P. Wiederrecht and E. R. Margine and I. I. Mazin and G. Karapetrov},
doi = {10.1103/PhysRevB.102.205139},
issn = {2469-9950},
year = {2020},
date = {2020-11-01},
journal = {PHYSICAL REVIEW B},
volume = {102},
number = {20},
publisher = {AMER PHYSICAL SOC},
address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
abstract = {We investigate carrier and collective mode dynamics in 2H-NbSe2 using
time-resolved optical pump-probe spectroscopy and compare the results
with first-principles calculations. Broadband ultrafast reflectivity
studies of 2H-NbSe2 in a wide temperature interval covering the normal,
charge density wave (CDW) and superconducting phase were performed.
Spectral features observed in the transient reflectivity experiment were
associated with specific optical transitions obtained from band
structure calculations. Displacive excitation of coherent phonons showed
CDW-associated coherent oscillations of the soft phonon mode across the
whole spectral range. Temperature evolution of this coherent phonon mode
in the low-excitation linear regime shows softening of the mode down to
the CDW transition temperature T-CDW with subsequent hardening below
T-CDW. The global fit of the broadband probe data reveals four different
relaxation times associated with characteristic electron-electron,
electron-phonon, and phonon-phonon relaxation processes. From
first-principles calculations of electron-phonon coupling we associate
the few picosecond electron-phonon relaxation time tau(2) with a
specific group of phonons with frequencies around 20 meV. On the other
hand, the anomalously long relaxation time of tau(3) similar to 100 ps
is associated with anharmonicity-driven phonon-phonon scattering. All
relaxation processes result from anomalies near the second order CDW
phase transition that are reflected in the temperature dependencies of
the characteristic relaxation times and amplitudes of coherent
oscillations. At the highest fluences we observe electronic melting of
the CDW and disappearance of the mode hardening below T-CDW.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
time-resolved optical pump-probe spectroscopy and compare the results
with first-principles calculations. Broadband ultrafast reflectivity
studies of 2H-NbSe2 in a wide temperature interval covering the normal,
charge density wave (CDW) and superconducting phase were performed.
Spectral features observed in the transient reflectivity experiment were
associated with specific optical transitions obtained from band
structure calculations. Displacive excitation of coherent phonons showed
CDW-associated coherent oscillations of the soft phonon mode across the
whole spectral range. Temperature evolution of this coherent phonon mode
in the low-excitation linear regime shows softening of the mode down to
the CDW transition temperature T-CDW with subsequent hardening below
T-CDW. The global fit of the broadband probe data reveals four different
relaxation times associated with characteristic electron-electron,
electron-phonon, and phonon-phonon relaxation processes. From
first-principles calculations of electron-phonon coupling we associate
the few picosecond electron-phonon relaxation time tau(2) with a
specific group of phonons with frequencies around 20 meV. On the other
hand, the anomalously long relaxation time of tau(3) similar to 100 ps
is associated with anharmonicity-driven phonon-phonon scattering. All
relaxation processes result from anomalies near the second order CDW
phase transition that are reflected in the temperature dependencies of
the characteristic relaxation times and amplitudes of coherent
oscillations. At the highest fluences we observe electronic melting of
the CDW and disappearance of the mode hardening below T-CDW.
Oliver, Sean M; Young, Joshua; Krylyuk, Sergiy; Reinecke, Thomas L; Davydov, Albert V; Vora, Patrick M
Valley phenomena in the candidate phase change material WSe2(1-x)Te2x Journal Article
In: COMMUNICATIONS PHYSICS, vol. 3, no. 1, 2020, ISSN: 2399-3650.
@article{ISI:000510920900001,
title = {Valley phenomena in the candidate phase change material WSe2(1-x)Te2x},
author = {Sean M Oliver and Joshua Young and Sergiy Krylyuk and Thomas L Reinecke and Albert V Davydov and Patrick M Vora},
doi = {10.1038/s42005-019-0277-7},
issn = {2399-3650},
year = {2020},
date = {2020-01-01},
journal = {COMMUNICATIONS PHYSICS},
volume = {3},
number = {1},
publisher = {NATURE PUBLISHING GROUP},
address = {MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND},
abstract = {Alloyed transition metal dichalcogenides provide a route toward
atomically-thin phase change memories that host valleytronic behaviours.
Here, Raman and photoluminescence spectroscopies are employed to
demonstrate the robustness of valley polarisation to chemical
substitution in monolayer alloys.
Alloyed transition metal dichalcogenides provide an opportunity for
coupling band engineering with valleytronic phenomena in an
atomically-thin platform. However, valley properties in alloys remain
largely unexplored. We investigate the valley degree of freedom in
monolayer alloys of the phase change candidate material WSe2(1-x)Te2x.
Low temperature Raman measurements track the alloy-induced transition
from the semiconducting 1H phase of WSe2 to the semimetallic 1T(d) phase
of WTe2. We correlate these observations with density functional theory
calculations and identify new Raman modes from W-Te vibrations in the
1H-phase alloy. Photoluminescence measurements show ultra-low energy
emission features that highlight alloy disorder arising from the large
W-Te bond lengths. Interestingly, valley polarization and coherence in
alloys survive at high Te compositions and are more robust against
temperature than in WSe2. These findings illustrate the persistence of
valley properties in alloys with highly dissimilar parent compounds and
suggest band engineering can be utilized for valleytronic devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
atomically-thin phase change memories that host valleytronic behaviours.
Here, Raman and photoluminescence spectroscopies are employed to
demonstrate the robustness of valley polarisation to chemical
substitution in monolayer alloys.
Alloyed transition metal dichalcogenides provide an opportunity for
coupling band engineering with valleytronic phenomena in an
atomically-thin platform. However, valley properties in alloys remain
largely unexplored. We investigate the valley degree of freedom in
monolayer alloys of the phase change candidate material WSe2(1-x)Te2x.
Low temperature Raman measurements track the alloy-induced transition
from the semiconducting 1H phase of WSe2 to the semimetallic 1T(d) phase
of WTe2. We correlate these observations with density functional theory
calculations and identify new Raman modes from W-Te vibrations in the
1H-phase alloy. Photoluminescence measurements show ultra-low energy
emission features that highlight alloy disorder arising from the large
W-Te bond lengths. Interestingly, valley polarization and coherence in
alloys survive at high Te compositions and are more robust against
temperature than in WSe2. These findings illustrate the persistence of
valley properties in alloys with highly dissimilar parent compounds and
suggest band engineering can be utilized for valleytronic devices.
2019
Chowdhury, Sugata; Hill, Heather; Simpson, Jeffrey; Vora, Patrick; Walker, Angela Hight; Tavazza, Francesca
DFT analysis of Raman modes in the CDW states of layered 2H-TaSe2 and 2H-TaS2 Journal Article
In: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, vol. 257, 2019, ISSN: 0065-7727, (National Meeting of the American-Chemical-Society (ACS), Orlando, FL, MAR 31-APR 04, 2019).
@article{ISI:000478860505402,
title = {DFT analysis of Raman modes in the CDW states of layered 2H-TaSe2 and
2H-TaS2},
author = {Sugata Chowdhury and Heather Hill and Jeffrey Simpson and Patrick Vora and Angela Hight Walker and Francesca Tavazza},
issn = {0065-7727},
year = {2019},
date = {2019-03-01},
journal = {ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY},
volume = {257},
publisher = {AMER CHEMICAL SOC},
address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA},
organization = {Amer Chem Soc},
note = {National Meeting of the American-Chemical-Society (ACS), Orlando, FL,
MAR 31-APR 04, 2019},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Hu, Haiping; Huang, Biao; Zhao, Erhai; Liu, Vincent W
Dynamical singularities of Floquet higher-order topological insulators Journal Article
In: 2019.
@article{Hu2019,
title = {Dynamical singularities of Floquet higher-order topological insulators},
author = {Haiping Hu and Biao Huang and Erhai Zhao and Vincent W Liu},
url = {http://arxiv.org/abs/1905.03727},
year = {2019},
date = {2019-05-01},
abstract = {We propose a versatile framework to dynamically generate Floquet higher-order topological insulators by multi-step driving of topologically trivial Hamiltonians. Two analytically solvable examples are used to illustrate this procedure to yield Floquet quadrupole and octupole insulators with zero- and/or $backslashpi$-corner modes protected by mirror symmetries. We introduce dynamical topological invariants from the full unitary return map and show its phase bands contain Weyl singularities whose topological charges form dynamical multipole moments in the Brillouin zone. Combining them with the topological index of Floquet Hamiltonian gives a pair of $backslashmathbbZ_2$ invariant $backslashnu_0$ and $backslashnu_backslashpi$ which fully characterize the higher-order topology and predict the appearance of zero- and $backslashpi$-corner modes. Our work establishes a systematic route to construct and characterize Floquet higher-order topological phases.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Zou, Haiyuan; Zhao, Erhai; Guan, Xi-Wen; Liu, Vincent W
Exactly Solvable Points and Symmetry Protected Topological Phases of Quantum Spins on a Zig-Zag Lattice Journal Article
In: Physical Review Letters, vol. 122, no. 18, pp. 180401, 2019, ISSN: 0031-9007.
@article{Zou2019,
title = {Exactly Solvable Points and Symmetry Protected Topological Phases of Quantum Spins on a Zig-Zag Lattice},
author = {Haiyuan Zou and Erhai Zhao and Xi-Wen Guan and Vincent W Liu},
url = {https://link.aps.org/doi/10.1103/PhysRevLett.122.180401},
doi = {10.1103/PhysRevLett.122.180401},
issn = {0031-9007},
year = {2019},
date = {2019-05-01},
journal = {Physical Review Letters},
volume = {122},
number = {18},
pages = {180401},
abstract = {A large number of symmetry-protected topological (SPT) phases have been hypothesized for strongly interacting spin-1/2 systems in one dimension. Realizing these SPT phases, however, often demands fine-tunings hard to reach experimentally. And the lack of analytical solutions hinders the understanding of their many-body wave functions. Here we show that two kinds of SPT phases naturally arise for ultracold polar molecules confined in a zigzag optical lattice. This system, motivated by recent experiments, is described by a spin model whose exchange couplings can be tuned by an external field to reach parameter regions not studied before for spin chains or ladders. Within the enlarged parameter space, we find the ground state wave function can be obtained exactly along a line and at a special point, for these two phases respectively. These exact solutions provide a clear physical picture for the SPT phases and their edge excitations. We further obtain the phase diagram by using infinite time-evolving block decimation, and discuss the phase transitions between the two SPT phases and their experimental signatures.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Shi, Chen; Rani, Asha; Thomson, Brian; Debnath, Ratan; Motayed, Abhishek; Ioannou, Dimitris E; Li, Qiliang
High-performance room-temperature TiO2-functionalized GaN nanowire gas sensors Journal Article
In: APPLIED PHYSICS LETTERS, vol. 115, no. 12, 2019, ISSN: 0003-6951.
@article{ISI:000487038900006,
title = {High-performance room-temperature TiO2-functionalized GaN nanowire gas
sensors},
author = {Chen Shi and Asha Rani and Brian Thomson and Ratan Debnath and Abhishek Motayed and Dimitris E Ioannou and Qiliang Li},
doi = {10.1063/1.5116677},
issn = {0003-6951},
year = {2019},
date = {2019-09-01},
journal = {APPLIED PHYSICS LETTERS},
volume = {115},
number = {12},
publisher = {AMER INST PHYSICS},
address = {1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA},
abstract = {Hybrid gas sensors based on TiO2 functionalized gallium nitride
nanowires have been prepared by nanofabrication and comprehensively
studied for high-responsivity applications. The devices exhibited a high
responsivity (25%) to 500 ppm NO2 assisted with ultraviolet
illumination at room temperature. The thickness and doping concentration
of TiO2 were engineered to improve the transducer function. The result
indicated that an excellent n-type response can be stably obtained for a
doping range from 1 x 10(17) cm(-3) to 1 x 10(19) cm(-3). The TiO2
thickness and doping concentration can be further fine-tuned to achieve
optimal performance. In addition, a comprehensive device simulation was
carried out to understand the device operation and gain insight for
optimizing the device performance.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
nanowires have been prepared by nanofabrication and comprehensively
studied for high-responsivity applications. The devices exhibited a high
responsivity (25%) to 500 ppm NO2 assisted with ultraviolet
illumination at room temperature. The thickness and doping concentration
of TiO2 were engineered to improve the transducer function. The result
indicated that an excellent n-type response can be stably obtained for a
doping range from 1 x 10(17) cm(-3) to 1 x 10(19) cm(-3). The TiO2
thickness and doping concentration can be further fine-tuned to achieve
optimal performance. In addition, a comprehensive device simulation was
carried out to understand the device operation and gain insight for
optimizing the device performance.
Jiang, Kai; Pookpanratana, Sujitra J; Ren, Tong; Natoli, Sean N; Sperling, Brent A; Robertson, Joseph; Richter, Curt A; Yu, Sheng; Li, Qiliang
Nonvolatile memory based on redox-active ruthenium molecular monolayers Journal Article
In: APPLIED PHYSICS LETTERS, vol. 115, no. 16, 2019, ISSN: 0003-6951.
@article{ISI:000503750200015,
title = {Nonvolatile memory based on redox-active ruthenium molecular monolayers},
author = {Kai Jiang and Sujitra J Pookpanratana and Tong Ren and Sean N Natoli and Brent A Sperling and Joseph Robertson and Curt A Richter and Sheng Yu and Qiliang Li},
doi = {10.1063/1.5108675},
issn = {0003-6951},
year = {2019},
date = {2019-10-01},
journal = {APPLIED PHYSICS LETTERS},
volume = {115},
number = {16},
publisher = {AMER INST PHYSICS},
address = {1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA},
abstract = {A monolayer of diruthenium molecules was self-assembled onto the silicon
oxide surface in a semiconductor capacitor structure with a ``click''
reaction for nonvolatile memory applications. The attachment of the
active molecular monolayer was verified by x-ray photoelectron
spectroscopy. The prototypical capacitor memory devices in this work
employed a metal/oxide/molecule/oxide/Si structure. With the intrinsic
redox-active charge-storage properties of diruthenium molecules, these
capacitor memory devices exhibited fast Program and Erase speed,
excellent endurance performance with negligible degradation of the
memory window after 10(5) program/erase cycles, and very good 10-year
memory retention. These experimental results indicate that the
redox-active ruthenium molecular memory is very promising for use in
nonvolatile memory applications. Published under license by AIP
Publishing.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
oxide surface in a semiconductor capacitor structure with a ``click''
reaction for nonvolatile memory applications. The attachment of the
active molecular monolayer was verified by x-ray photoelectron
spectroscopy. The prototypical capacitor memory devices in this work
employed a metal/oxide/molecule/oxide/Si structure. With the intrinsic
redox-active charge-storage properties of diruthenium molecules, these
capacitor memory devices exhibited fast Program and Erase speed,
excellent endurance performance with negligible degradation of the
memory window after 10(5) program/erase cycles, and very good 10-year
memory retention. These experimental results indicate that the
redox-active ruthenium molecular memory is very promising for use in
nonvolatile memory applications. Published under license by AIP
Publishing.
Zhu, Hao; Richter, Curt A; Yu, Sheng; Ye, Huixian; Zeng, Min; Li, Qiliang
Observation and control of the anomalous Aharonov-Bohm oscillation in enhanced-mode topological insulator nanowire field-effect transistors Journal Article
In: APPLIED PHYSICS LETTERS, vol. 115, no. 7, 2019, ISSN: 0003-6951.
@article{ISI:000481469900038,
title = {Observation and control of the anomalous Aharonov-Bohm oscillation in
enhanced-mode topological insulator nanowire field-effect transistors},
author = {Hao Zhu and Curt A Richter and Sheng Yu and Huixian Ye and Min Zeng and Qiliang Li},
doi = {10.1063/1.5111180},
issn = {0003-6951},
year = {2019},
date = {2019-08-01},
journal = {APPLIED PHYSICS LETTERS},
volume = {115},
number = {7},
publisher = {AMER INST PHYSICS},
address = {1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA},
abstract = {Aharonov-Bohm (AB) oscillation is a quantum mechanical phenomenon which
reveals the coupling of electromagnetic potentials with the electron
wave function, affecting the phase of the wave function. Such a quantum
interference effect can be demonstrated through the magnetotransport
measurement focusing on low-dimensional electronic states. Here, we
report the experimental observation of anomalous AB oscillation in an
enhanced-mode topological insulator Bi2Se3 nanowire field-effect
transistor (FET) under strong surface disorder, which is different from
the reported AB oscillation in topological insulator nanostructures. The
surrounding gate of the nanowire FET gives rise to tunability of the
chemical potential and introduces strong disorder on the surface states,
leading to primary oscillation with an anomalous h/e period.
Furthermore, the oscillation exhibits a significant dependence on the
gate voltage which has been preliminary explained with the quantization
of the surface conduction channel. The experimental demonstration can be
very attractive for further exploration of quantum phase interference
through electrical approaches, enabling applications in future
information and electromagnetic sensing technology.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
reveals the coupling of electromagnetic potentials with the electron
wave function, affecting the phase of the wave function. Such a quantum
interference effect can be demonstrated through the magnetotransport
measurement focusing on low-dimensional electronic states. Here, we
report the experimental observation of anomalous AB oscillation in an
enhanced-mode topological insulator Bi2Se3 nanowire field-effect
transistor (FET) under strong surface disorder, which is different from
the reported AB oscillation in topological insulator nanostructures. The
surrounding gate of the nanowire FET gives rise to tunability of the
chemical potential and introduces strong disorder on the surface states,
leading to primary oscillation with an anomalous h/e period.
Furthermore, the oscillation exhibits a significant dependence on the
gate voltage which has been preliminary explained with the quantization
of the surface conduction channel. The experimental demonstration can be
very attractive for further exploration of quantum phase interference
through electrical approaches, enabling applications in future
information and electromagnetic sensing technology.
Keles, Ahmet; Zhao, Erhai; Li, Xiaopeng
Phase diagram of Rydberg-dressed Fermi gas in two dimensions Journal Article
In: 2019.
@article{Keles2019a,
title = {Phase diagram of Rydberg-dressed Fermi gas in two dimensions},
author = {Ahmet Keles and Erhai Zhao and Xiaopeng Li},
url = {http://arxiv.org/abs/1906.04235},
year = {2019},
date = {2019-06-01},
abstract = {Rydberg-dressed ultracold Fermi gas is one of the latest quantum many-body systems where the sign, strength, and range of the interaction can be controlled experimentally. The interaction in momentum space has a negative minimum at $q_c$ inversely proportional to the characteristic length-scale in real space, the soft-core radius $r_c$. We show theoretically that single-component (spinless) Rydberg-dressed Fermi gas in two dimensions has a rich phase diagram with novel superfluid and density wave orders due to the interplay of the Fermi momentum $p_F$, interaction range $r_c$, and interaction strength $u_0$. For repulsive bare interactions $u_0textgreater0$, the dominant instability is $f$-wave superfluid for $p_Fr_cbackslashlesssim 2$, and density wave for $p_Fr_cbackslashgtrsim 4$. The $f$-wave pairing in a repulsive Fermi gas is reminiscent of, but differs from, the conventional Kohn-Luttinger mechanism. For attractive bare interactions $u_0textless0$, the leading instability is $p$-wave pairing with double degeneracy, which points to a $p_x+ip_y$ topological superfluid. The phase diagram is obtained from functional renormalization group with high momentum resolution. It treats all competing many-body instabilities in the particle-particle and particle-hole channels on equal footing beyond leading order perturbation theory and random-phase approximation.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Yu, Sheng; Tabibi, Bagher; Li, Qiliang; Seo, Felix Jaetae
Piezoelectric enhancement of a defect-mediated boron nitride nanotube Journal Article
In: JOURNAL OF PHYSICS D-APPLIED PHYSICS, vol. 52, no. 33, 2019, ISSN: 0022-3727.
@article{ISI:000471987400002,
title = {Piezoelectric enhancement of a defect-mediated boron nitride nanotube},
author = {Sheng Yu and Bagher Tabibi and Qiliang Li and Felix Jaetae Seo},
doi = {10.1088/1361-6463/ab2582},
issn = {0022-3727},
year = {2019},
date = {2019-08-01},
journal = {JOURNAL OF PHYSICS D-APPLIED PHYSICS},
volume = {52},
number = {33},
publisher = {IOP PUBLISHING LTD},
address = {TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND},
abstract = {A zigzag boron nitride nanotube (ZBNNT) has a large intrinsic polarized
dipole and a piezoelectric tunability with crystal chirality, nanotube
diameter, and point defect. The piezoelectric coefficients (e(33)) of
8-ZBNNT with the VIA-group defects of S-N and Se-N are estimated to be
18.7 x 10(-2) C m(-2) and 14.9 x 10(-2) C m(-2), respectively. The
coefficients of defect-mediated 8-ZBNNT are 97% and 57% bigger than
that of pristine 8-ZBNNT. The elastic modulus of 8-ZBNNT is decreased
due to the VIA-group defects, but is increased for the larger number of
unit cells along zigzag rolling direction. The electronic band gap of
8-ZBNNT is reduced due to the VIA-group defects. The large
piezoelectricity enhancement of 8-ZBNNT with VIA-group defect is
attributable to the ionic contribution. Therefore, the unprecedented
defect-mediated 8-ZBNNT provides a new material platform of
mechanoelectronic devices for nanoscale sensors and energy conversions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
dipole and a piezoelectric tunability with crystal chirality, nanotube
diameter, and point defect. The piezoelectric coefficients (e(33)) of
8-ZBNNT with the VIA-group defects of S-N and Se-N are estimated to be
18.7 x 10(-2) C m(-2) and 14.9 x 10(-2) C m(-2), respectively. The
coefficients of defect-mediated 8-ZBNNT are 97% and 57% bigger than
that of pristine 8-ZBNNT. The elastic modulus of 8-ZBNNT is decreased
due to the VIA-group defects, but is increased for the larger number of
unit cells along zigzag rolling direction. The electronic band gap of
8-ZBNNT is reduced due to the VIA-group defects. The large
piezoelectricity enhancement of 8-ZBNNT with VIA-group defect is
attributable to the ionic contribution. Therefore, the unprecedented
defect-mediated 8-ZBNNT provides a new material platform of
mechanoelectronic devices for nanoscale sensors and energy conversions.
Zhang, Kehao; Wang, Yuanxi; Joshi, Jaydeep; Zhang, Fu; Subramanian, Shruti; Terrones, Mauricio; Vora, Patrick; Crespi, Vincent; Robinson, Joshua A
Probing the origin of lateral heterogeneities in synthetic monolayer molybdenum disulfide Journal Article
In: 2D Materials, vol. 6, no. 2, pp. 025008, 2019, ISSN: 2053-1583.
@article{Zhang2019b,
title = {Probing the origin of lateral heterogeneities in synthetic monolayer molybdenum disulfide},
author = {Kehao Zhang and Yuanxi Wang and Jaydeep Joshi and Fu Zhang and Shruti Subramanian and Mauricio Terrones and Patrick Vora and Vincent Crespi and Joshua A Robinson},
url = {http://iopscience.iop.org/article/10.1088/2053-1583/aafd9a http://stacks.iop.org/2053-1583/6/i=2/a=025008?key=crossref.006e7cddfc7a7f13021280ae38e90026},
doi = {10.1088/2053-1583/aafd9a},
issn = {2053-1583},
year = {2019},
date = {2019-02-01},
journal = {2D Materials},
volume = {6},
number = {2},
pages = {025008},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Keleş, Ahmet; Zhao, Erhai; Liu, Vincent W
Scrambling dynamics and many-body chaos in a random dipolar spin model Journal Article
In: Physical Review A, vol. 99, no. 5, pp. 053620, 2019, ISSN: 2469-9926.
@article{Keles2019b,
title = {Scrambling dynamics and many-body chaos in a random dipolar spin model},
author = {Ahmet Kele\c{s} and Erhai Zhao and Vincent W Liu},
url = {https://link.aps.org/doi/10.1103/PhysRevA.99.053620},
doi = {10.1103/PhysRevA.99.053620},
issn = {2469-9926},
year = {2019},
date = {2019-05-01},
journal = {Physical Review A},
volume = {99},
number = {5},
pages = {053620},
abstract = {Is there a quantum many-body system that scrambles information as fast as a black hole? The Sachev-Ye-Kitaev model can saturate the conjectured bound for chaos, but it requires random all-to-all couplings of Majorana fermions that are hard to realize in experiments. Here we examine a quantum spin model of randomly oriented dipoles where the spin exchange is governed by dipole-dipole interactions. The model is inspired by recent experiments on dipolar spin systems of magnetic atoms, dipolar molecules, and nitrogen-vacancy centers. We map out the phase diagram of this model by computing the energy level statistics, spectral form factor, and out-of-time-order correlation (OTOC) functions. We find a broad regime of many-body chaos where the energy levels obey Wigner-Dyson statistics and the OTOC shows distinctive behaviors at different times: Its early-time dynamics is characterized by an exponential growth, while the approach to its saturated value at late times obeys a power law. The temperature scaling of the Lyapunov exponent $backslashlambda_L$ shows that while it is well below the conjectured bound $2backslashpi T$ at high temperatures, $backslashlambda_L$ approaches the bound at low temperatures and for large number of spins.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Joshi, Jaydeep; Hill, Heather M; Chowdhury, Sugata; Malliakas, Christos D; Tavazza, Francesca; Chatterjee, Utpal; Walker, Angela Hight R; Vora, Patrick M
Short-range charge density wave order in 2H-TaS2 Journal Article
In: PHYSICAL REVIEW B, vol. 99, no. 24, 2019, ISSN: 2469-9950.
@article{ISI:000473018900001,
title = {Short-range charge density wave order in 2H-TaS2},
author = {Jaydeep Joshi and Heather M Hill and Sugata Chowdhury and Christos D Malliakas and Francesca Tavazza and Utpal Chatterjee and Angela Hight R Walker and Patrick M Vora},
doi = {10.1103/PhysRevB.99.245144},
issn = {2469-9950},
year = {2019},
date = {2019-06-01},
journal = {PHYSICAL REVIEW B},
volume = {99},
number = {24},
publisher = {AMER PHYSICAL SOC},
address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
abstract = {2H-TaS2 undergoes a charge density wave (CDW) transition at T-CDW
similar to 75 K, however key questions regarding the onset of CDWorder
remain under debate. In this study, we explore the CDWtransition through
a combination of temperature and excitation-dependent Raman
spectroscopy, angle resolved photoemission spectroscopy (ARPES), and
density functional theory (DFT). Below T-CDW we identify two CDW
amplitude modes that redshift and broaden with increasing temperature
and one zone-folded mode that disappears above T-CDW. Above T-CDW, we
observe a strong two-phonon mode that softens substantially upon
cooling, which suggests the presence of substantial lattice distortions
at temperatures as high as 250 K. This correlates with the ARPES
observation of the persistence of a CDW energy gap above T-CDW and
finite-temperature DFT calculations of the phonon band structure that
indicate an instability occurring well above the CDW transition
temperature. DFT also provides the atomic displacements of the CDW
amplitude modes and reproduces their temperature dependence. From these
observations we suggest that short range CDW order exists well above
T-CDW, which poses new questions regarding the interplay between
electronic structure and vibrational modes in layered CDW materials.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
similar to 75 K, however key questions regarding the onset of CDWorder
remain under debate. In this study, we explore the CDWtransition through
a combination of temperature and excitation-dependent Raman
spectroscopy, angle resolved photoemission spectroscopy (ARPES), and
density functional theory (DFT). Below T-CDW we identify two CDW
amplitude modes that redshift and broaden with increasing temperature
and one zone-folded mode that disappears above T-CDW. Above T-CDW, we
observe a strong two-phonon mode that softens substantially upon
cooling, which suggests the presence of substantial lattice distortions
at temperatures as high as 250 K. This correlates with the ARPES
observation of the persistence of a CDW energy gap above T-CDW and
finite-temperature DFT calculations of the phonon band structure that
indicate an instability occurring well above the CDW transition
temperature. DFT also provides the atomic displacements of the CDW
amplitude modes and reproduces their temperature dependence. From these
observations we suggest that short range CDW order exists well above
T-CDW, which poses new questions regarding the interplay between
electronic structure and vibrational modes in layered CDW materials.
Vora, Patrick M; Bracker, Allan S; Carter, Samuel G; Kim, Mijin; Kim, Chul Soo; Gammon, Daniel
Strong coupling of a quantum dot molecule to a photonic crystal cavity Journal Article
In: Physical Review B, vol. 99, no. 16, pp. 165420, 2019, ISSN: 2469-9950.
@article{Vora2019,
title = {Strong coupling of a quantum dot molecule to a photonic crystal cavity},
author = {Patrick M Vora and Allan S Bracker and Samuel G Carter and Mijin Kim and Chul Soo Kim and Daniel Gammon},
url = {https://link.aps.org/doi/10.1103/PhysRevB.99.165420},
doi = {10.1103/PhysRevB.99.165420},
issn = {2469-9950},
year = {2019},
date = {2019-04-01},
journal = {Physical Review B},
volume = {99},
number = {16},
pages = {165420},
publisher = {American Physical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Ansari, Jaafar N; Sauer, Karen L; Glasbrenner, James K
The Predictive Power of Different Projector-Augmented Wave Potentials for Nuclear Quadrupole Resonance Journal Article
In: CRYSTALS, vol. 9, no. 10, 2019, ISSN: 2073-4352.
@article{ISI:000498263500022,
title = {The Predictive Power of Different Projector-Augmented Wave Potentials
for Nuclear Quadrupole Resonance},
author = {Jaafar N Ansari and Karen L Sauer and James K Glasbrenner},
doi = {10.3390/cryst9100507},
issn = {2073-4352},
year = {2019},
date = {2019-10-01},
journal = {CRYSTALS},
volume = {9},
number = {10},
publisher = {MDPI},
address = {ST ALBAN-ANLAGE 66, CH-4052 BASEL, SWITZERLAND},
abstract = {The projector-augmented wave (PAW) method is used to calculate electric
field gradients (EFG) for various PAW potentials. A variety of crystals
containing reactive nonmetal, simple metal, and transition elements, are
evaluated in order to determine the predictive ability of the PAW method
for the determination of nuclear quadrupole resonance frequencies in
previously unstudied materials and their polymorphs. All results were
compared to experimental results and, where possible, to previous
density functional theory (DFT) calculations. The EFG at the N-14 site
of NaNO2 is calculated by DFT for the first time. The reactive nonmetal
elements were not very sensitive to the variation in PAW potentials, and
calculations were quite close to experimental values. For the other
elements, the various PAW potentials led to a clear spread in EFG
values, with no one universal potential emerging. Within the spread,
there was agreement with other ab initio models.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
field gradients (EFG) for various PAW potentials. A variety of crystals
containing reactive nonmetal, simple metal, and transition elements, are
evaluated in order to determine the predictive ability of the PAW method
for the determination of nuclear quadrupole resonance frequencies in
previously unstudied materials and their polymorphs. All results were
compared to experimental results and, where possible, to previous
density functional theory (DFT) calculations. The EFG at the N-14 site
of NaNO2 is calculated by DFT for the first time. The reactive nonmetal
elements were not very sensitive to the variation in PAW potentials, and
calculations were quite close to experimental values. For the other
elements, the various PAW potentials led to a clear spread in EFG
values, with no one universal potential emerging. Within the spread,
there was agreement with other ab initio models.
Takeda, H; Yasuoka, H; Yoshida, M; Takigawa, M; Ghimire, N J; Mandrus, D; Sales, B C
V-51-NMR study on the S=1/2 square lattice antiferromagnet K2V3O8 Journal Article
In: PHYSICAL REVIEW B, vol. 100, no. 5, 2019, ISSN: 2469-9950.
@article{ISI:000478991000003,
title = {V-51-NMR study on the S=1/2 square lattice antiferromagnet K2V3O8},
author = {H Takeda and H Yasuoka and M Yoshida and M Takigawa and N J Ghimire and D Mandrus and B C Sales},
doi = {10.1103/PhysRevB.100.054406},
issn = {2469-9950},
year = {2019},
date = {2019-08-01},
journal = {PHYSICAL REVIEW B},
volume = {100},
number = {5},
publisher = {AMER PHYSICAL SOC},
address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
abstract = {Static and dynamic properties of the quasi-two-dimensional
antiferromagnet K2V3O8 have been investigated by V-51-NMR experiments on nonmagnetic V5+ sites. Above the structural transition temperature T-S =
115 K, NMR spectra are fully compatible with the P4bm space-group
symmetry. The formation of superstructure below T-S causes splitting of
the NMR lines, which get broadened at lower temperatures so that
individual peaks are not well resolved. Evolution of NMR spectra with
magnetic field along the c axis below the magnetic transition
temperature T-N similar to 4 K is qualitatively consistent with a simple
Neel order and a spin-flop transition. However, a broad feature of the
spectra does not rule out possible incommensurate spin structure. The
spin-lattice relaxation rate 1/T-1 below T-N shows huge enhancement for
a certain range of magnetic field, which is independent of temperature
and attributed to cross relaxation due to anomalously large nuclear
spin-spin coupling between V5+ and magnetic V4+ sites. The results
indicate strong gapless spin fluctuations, which could arise from
incommensurate orders or complex spin textures.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
antiferromagnet K2V3O8 have been investigated by V-51-NMR experiments on nonmagnetic V5+ sites. Above the structural transition temperature T-S =
115 K, NMR spectra are fully compatible with the P4bm space-group
symmetry. The formation of superstructure below T-S causes splitting of
the NMR lines, which get broadened at lower temperatures so that
individual peaks are not well resolved. Evolution of NMR spectra with
magnetic field along the c axis below the magnetic transition
temperature T-N similar to 4 K is qualitatively consistent with a simple
Neel order and a spin-flop transition. However, a broad feature of the
spectra does not rule out possible incommensurate spin structure. The
spin-lattice relaxation rate 1/T-1 below T-N shows huge enhancement for
a certain range of magnetic field, which is independent of temperature
and attributed to cross relaxation due to anomalously large nuclear
spin-spin coupling between V5+ and magnetic V4+ sites. The results
indicate strong gapless spin fluctuations, which could arise from
incommensurate orders or complex spin textures.
Oliver, Sean M; Young, Joshua; Krylyuk, Sergiy; Reinecke, Thomas L; Davydov, Albert V; Vora, Patrick M
Valley Phenomena in the Candidate Phase Change Material WSe$_2(1-x)$Te$_2x$ Journal Article
In: 2019.
@article{Oliver2019,
title = {Valley Phenomena in the Candidate Phase Change Material WSe$_2(1-x)$Te$_2x$},
author = {Sean M Oliver and Joshua Young and Sergiy Krylyuk and Thomas L Reinecke and Albert V Davydov and Patrick M Vora},
url = {http://arxiv.org/abs/1908.00506},
year = {2019},
date = {2019-08-01},
abstract = {Alloyed transition metal dichalcogenides provide a unique opportunity for coupling band engineering and valleytronic phenomena in an atomically-thin platform. However, valley properties in alloys remain largely unexplored. We investigate the valley degree of freedom in monolayer alloys of the phase change candidate material WSe$_2(1-x)$Te$_2x$. Low temperature Raman measurements track the alloy-induced transition from the semiconducting 1H phase of WSe$_2$ to the semimetallic 1T$_d$ phase of WTe$_2$. We correlate these observations with density functional theory calculations and identify new Raman modes from 1H-WTe$_2$. Photoluminescence measurements show ultra-low energy emission features that highlight the presence of significant alloy disorder arising from the large W-Te bond lengths. Interestingly, valley polarization and coherence in alloys survive at high Te compositions and are more robust against temperature than in WSe$_2$. These findings illustrate the persistence of valley properties in alloys with highly dissimilar parent compounds and suggest band engineering can be utilized for valleytronic devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2018
Keleş, Ahmet; Zhao, Erhai
Absence of Long-Range Order in a Triangular Spin System with Dipolar Interactions Journal Article
In: Physical Review Letters, vol. 120, no. 18, pp. 187202, 2018, ISSN: 0031-9007.
@article{PhysRevLett.120.187202,
title = {Absence of Long-Range Order in a Triangular Spin System with Dipolar Interactions},
author = {Ahmet Kele\c{s} and Erhai Zhao},
url = {https://link.aps.org/doi/10.1103/PhysRevLett.120.187202},
doi = {10.1103/PhysRevLett.120.187202},
issn = {0031-9007},
year = {2018},
date = {2018-05-01},
journal = {Physical Review Letters},
volume = {120},
number = {18},
pages = {187202},
publisher = {American Physical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Zhao, K; Glasbrenner, J K; Gretarsson, H; Schmitz, D; Bednarcik, J; Etter, M; Sun, J P; Manna, R S; Al-Zein, A; Lafuerza, S; Scherer, W; Cheng, J G; Gegenwart, P
In: Physical Review B, vol. 97, no. 2, pp. 020510, 2018, ISSN: 2469-9950.
@article{Zhao2018_PRBRC_Collapsed,
title = {Collapsed tetragonal phase as a strongly covalent and fully nonmagnetic state: Persistent magnetism with interlayer As\textendashAs bond formation in Rh-doped Ca0.8 Sr0.2 Fe2 As2},
author = {K Zhao and J K Glasbrenner and H Gretarsson and D Schmitz and J Bednarcik and M Etter and J P Sun and R S Manna and A Al-Zein and S Lafuerza and W Scherer and J G Cheng and P Gegenwart},
url = {https://link.aps.org/doi/10.1103/PhysRevB.97.020510},
doi = {10.1103/PhysRevB.97.020510},
issn = {2469-9950},
year = {2018},
date = {2018-01-01},
journal = {Physical Review B},
volume = {97},
number = {2},
pages = {020510},
publisher = {American Physical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Díaz, Sebastián A; Oliver, Sean M; Hastman, David A; Medintz, Igor L; Vora, Patrick M
Increased Transfer Efficiency from Molecular Photonic Wires on Solid Substrates and Cryogenic Conditions Journal Article
In: The Journal of Physical Chemistry Letters, vol. 9, no. 13, pp. 3654–3659, 2018, ISSN: 1948-7185.
@article{Diaz2018,
title = {Increased Transfer Efficiency from Molecular Photonic Wires on Solid Substrates and Cryogenic Conditions},
author = {Sebasti\'{a}n A D\'{i}az and Sean M Oliver and David A Hastman and Igor L Medintz and Patrick M Vora},
url = {http://pubs.acs.org/doi/10.1021/acs.jpclett.8b00931},
doi = {10.1021/acs.jpclett.8b00931},
issn = {1948-7185},
year = {2018},
date = {2018-07-01},
journal = {The Journal of Physical Chemistry Letters},
volume = {9},
number = {13},
pages = {3654--3659},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Díaz, Sebastián A; Oliver, Sean M; Hastman, David A; Medintz, Igor L; Vora, Patrick M
Increased Transfer Efficiency from Molecular Photonic Wires on Solid Substrates and Cryogenic Conditions Journal Article
In: The Journal of Physical Chemistry Letters, vol. 9, no. 13, pp. 3654–3659, 2018, ISSN: 1948-7185.
@article{Diaz2018b,
title = {Increased Transfer Efficiency from Molecular Photonic Wires on Solid Substrates and Cryogenic Conditions},
author = {Sebasti\'{a}n A D\'{i}az and Sean M Oliver and David A Hastman and Igor L Medintz and Patrick M Vora},
url = {http://pubs.acs.org/doi/10.1021/acs.jpclett.8b00931},
doi = {10.1021/acs.jpclett.8b00931},
issn = {1948-7185},
year = {2018},
date = {2018-07-01},
journal = {The Journal of Physical Chemistry Letters},
volume = {9},
number = {13},
pages = {3654--3659},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Kang, Pilgyu; Kim, Kyoung-Ho; Park, Hong-Gyu; Nam, SungWoo
Mechanically reconfigurable architectured graphene for tunable plasmonic resonances Journal Article
In: Light: Science & Applications, vol. 7, no. 1, pp. 17, 2018, ISSN: 2047-7538.
@article{Kang2018a,
title = {Mechanically reconfigurable architectured graphene for tunable plasmonic resonances},
author = {Pilgyu Kang and Kyoung-Ho Kim and Hong-Gyu Park and SungWoo Nam},
url = {http://www.nature.com/articles/s41377-018-0002-4},
doi = {10.1038/s41377-018-0002-4},
issn = {2047-7538},
year = {2018},
date = {2018-12-01},
journal = {Light: Science \& Applications},
volume = {7},
number = {1},
pages = {17},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Vega, Devin; Tian, Mingzhen
Photon echoes from an atomic frequency comb affected by population relaxation Journal Article
In: Physical Review A, vol. 98, no. 5, pp. 052340, 2018, ISSN: 2469-9926.
@article{Vega2018a,
title = {Photon echoes from an atomic frequency comb affected by population relaxation},
author = {Devin Vega and Mingzhen Tian},
url = {https://link.aps.org/doi/10.1103/PhysRevA.98.052340},
doi = {10.1103/PhysRevA.98.052340},
issn = {2469-9926},
year = {2018},
date = {2018-11-01},
journal = {Physical Review A},
volume = {98},
number = {5},
pages = {052340},
abstract = {textcopyright 2018 American Physical Society. The atomic frequency comb (AFC) is a promising approach for quantum memory, yet creating an ideal AFC only in the ground-state population remains a challenge. We studied an imperfect AFC initially created in the population inversion between the excited and ground states and redistributed due to population relaxation in a three-level system where a long-lived metastable state plays a crucial role. A theoretical model has been developed to treat the storage of a weak input pulse and retrieval in the form of a photon echo. By comparing theory with experimental results we have studied the echo efficiency and overall attenuation of an input pulse in the AFC affected by both its initial spectral structure and the population relaxation.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Keleş, Ahmet; Zhao, Erhai
Renormalization group analysis of dipolar Heisenberg model on square lattice Journal Article
In: Physical Review B, vol. 97, no. 24, pp. 245105, 2018, ISSN: 2469-9950.
@article{PhysRevB.97.245105,
title = {Renormalization group analysis of dipolar Heisenberg model on square lattice},
author = {Ahmet Kele\c{s} and Erhai Zhao},
url = {https://link.aps.org/doi/10.1103/PhysRevB.97.245105},
doi = {10.1103/PhysRevB.97.245105},
issn = {2469-9950},
year = {2018},
date = {2018-06-01},
journal = {Physical Review B},
volume = {97},
number = {24},
pages = {245105},
publisher = {American Physical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Cooper, Robert J; Prescott, David W; Lee, Garrett J; Sauer, Karen L
RF atomic magnetometer array with over 40 dB interference suppression using electron spin resonance Journal Article
In: Journal of Magnetic Resonance, 2018, ISSN: 10907807.
@article{COOPER2018,
title = {RF atomic magnetometer array with over 40 dB interference suppression using electron spin resonance},
author = {Robert J Cooper and David W Prescott and Garrett J Lee and Karen L Sauer},
url = {http://www.sciencedirect.com/science/article/pii/S1090780718302118 https://linkinghub.elsevier.com/retrieve/pii/S1090780718302118},
doi = {10.1016/j.jmr.2018.08.007},
issn = {10907807},
year = {2018},
date = {2018-08-01},
journal = {Journal of Magnetic Resonance},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Zhang, Kehao; Bersch, Brian M; Joshi, Jaydeep; Addou, Rafik; Cormier, Christopher R; Zhang, Chenxi; Xu, Ke; Briggs, Natalie C; Wang, Ke; Subramanian, Shruti; Cho, Kyeongjae; Fullerton-Shirey, Susan; Wallace, Robert M; Vora, Patrick M; Robinson, Joshua A
Tuning the Electronic and Photonic Properties of Monolayer MoS 2 via In Situ Rhenium Substitutional Doping Journal Article
In: Advanced Functional Materials, vol. 28, no. 16, pp. 1706950, 2018, ISSN: 1616301X.
@article{Zhang2018db,
title = {Tuning the Electronic and Photonic Properties of Monolayer MoS 2 via In Situ Rhenium Substitutional Doping},
author = {Kehao Zhang and Brian M Bersch and Jaydeep Joshi and Rafik Addou and Christopher R Cormier and Chenxi Zhang and Ke Xu and Natalie C Briggs and Ke Wang and Shruti Subramanian and Kyeongjae Cho and Susan Fullerton-Shirey and Robert M Wallace and Patrick M Vora and Joshua A Robinson},
url = {http://doi.wiley.com/10.1002/adfm.201706950},
doi = {10.1002/adfm.201706950},
issn = {1616301X},
year = {2018},
date = {2018-04-01},
journal = {Advanced Functional Materials},
volume = {28},
number = {16},
pages = {1706950},
abstract = {textcopyright 2018 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim. Doping is a fundamental requirement for tuning and improving the properties of conventional semiconductors. Recent doping studies including niobium (Nb) doping of molybdenum disulfide (MoS 2 ) and tungsten (W) doping of molybdenum diselenide (MoSe 2 ) have suggested that substitutional doping may provide an efficient route to tune the doping type and suppress deep trap levels of 2D materials. To date, the impact of the doping on the structural, electronic, and photonic properties of in situ-doped monolayers remains unanswered due to challenges including strong film substrate charge transfer, and difficulty achieving doping concentrations greater than 0.3 at%. Here, in situ rhenium (Re) doping of synthetic monolayer MoS 2 with ≈1 at% Re is demonstrated. To limit substrate film charge transfer, r-plane sapphire is used. Electronic measurements demonstrate that 1 at% Re doping achieves nearly degenerate n-type doping, which agrees with density functional theory calculations. Moreover, low-temperature photoluminescence indicates a significant quench of the defect-bound emission when Re is introduced, which is attributed to the Mo-O bond and sulfur vacancies passivation and reduction in gap states due to the presence of Re. The work presented here demonstrates that Re doping of MoS 2 is a promising route toward electronic and photonic engineering of 2D materials.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Zhang, Kehao; Bersch, Brian M; Joshi, Jaydeep; Addou, Rafik; Cormier, Christopher R; Zhang, Chenxi; Xu, Ke; Briggs, Natalie C; Wang, Ke; Subramanian, Shruti; Cho, Kyeongjae; Fullerton-Shirey, Susan; Wallace, Robert M; Vora, Patrick M; Robinson, Joshua A
Tuning the Electronic and Photonic Properties of Monolayer MoS2 via In Situ Rhenium Substitutional Doping Journal Article
In: Advanced Functional Materials, vol. 28, no. 16, pp. 1706950, 2018, ISSN: 1616301X.
@article{Zhang2018d,
title = {Tuning the Electronic and Photonic Properties of Monolayer MoS2 via In Situ Rhenium Substitutional Doping},
author = {Kehao Zhang and Brian M Bersch and Jaydeep Joshi and Rafik Addou and Christopher R Cormier and Chenxi Zhang and Ke Xu and Natalie C Briggs and Ke Wang and Shruti Subramanian and Kyeongjae Cho and Susan Fullerton-Shirey and Robert M Wallace and Patrick M Vora and Joshua A Robinson},
url = {http://doi.wiley.com/10.1002/adfm.201706950},
doi = {10.1002/adfm.201706950},
issn = {1616301X},
year = {2018},
date = {2018-04-01},
journal = {Advanced Functional Materials},
volume = {28},
number = {16},
pages = {1706950},
abstract = {textcopyright 2018 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim. Doping is a fundamental requirement for tuning and improving the properties of conventional semiconductors. Recent doping studies including niobium (Nb) doping of molybdenum disulfide (MoS 2 ) and tungsten (W) doping of molybdenum diselenide (MoSe 2 ) have suggested that substitutional doping may provide an efficient route to tune the doping type and suppress deep trap levels of 2D materials. To date, the impact of the doping on the structural, electronic, and photonic properties of in situ-doped monolayers remains unanswered due to challenges including strong film substrate charge transfer, and difficulty achieving doping concentrations greater than 0.3 at%. Here, in situ rhenium (Re) doping of synthetic monolayer MoS 2 with ≈1 at% Re is demonstrated. To limit substrate film charge transfer, r-plane sapphire is used. Electronic measurements demonstrate that 1 at% Re doping achieves nearly degenerate n-type doping, which agrees with density functional theory calculations. Moreover, low-temperature photoluminescence indicates a significant quench of the defect-bound emission when Re is introduced, which is attributed to the Mo-O bond and sulfur vacancies passivation and reduction in gap states due to the presence of Re. The work presented here demonstrates that Re doping of MoS 2 is a promising route toward electronic and photonic engineering of 2D materials.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Keles, Ahmet; Zhao, Erhai
Weyl nodes in periodic structures of superconductors and spin-active materials Journal Article
In: Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol. 376, no. 2125, pp. 20150151, 2018, ISSN: 1364-503X.
@article{Keles2018,
title = {Weyl nodes in periodic structures of superconductors and spin-active materials},
author = {Ahmet Keles and Erhai Zhao},
url = {https://doi.org/10.1098/rsta.2015.0151 http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2015.0151},
doi = {10.1098/rsta.2015.0151},
issn = {1364-503X},
year = {2018},
date = {2018-08-01},
journal = {Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences},
volume = {376},
number = {2125},
pages = {20150151},
publisher = {The Royal Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2017
Kim, Minsu; Kang, Pilgyu; Leem, Juyoung; Nam, SungWoo
A stretchable crumpled graphene photodetector with plasmonically enhanced photoresponsivity Journal Article
In: Nanoscale, vol. 9, no. 12, pp. 4058–4065, 2017, ISSN: 2040-3364.
@article{Kim2017c,
title = {A stretchable crumpled graphene photodetector with plasmonically enhanced photoresponsivity},
author = {Minsu Kim and Pilgyu Kang and Juyoung Leem and SungWoo Nam},
url = {http://xlink.rsc.org/?DOI=C6NR09338H},
doi = {10.1039/C6NR09338H},
issn = {2040-3364},
year = {2017},
date = {2017-01-01},
journal = {Nanoscale},
volume = {9},
number = {12},
pages = {4058--4065},
abstract = {Graphene has been widely explored for flexible, high-performance photodetectors due to its exceptional mechanical strength, broadband absorption, and high carrier mobility. However, the low stretchability and limited photoabsorption of graphene have restricted its applications in flexible and highly sensitive photodetection systems. Various hybrid systems based on photonic or plasmonic nanostructures have been introduced to improve the limited photoresponsivity of graphene photodetectors. In most cases, the hybrid systems succeeded in the enhancement of photoresponsivity, but showed limited mechanical stretchability. Here, we demonstrate a stretchable photodetector based on a crumpled graphene\textendashgold nanoparticle (AuNP) hybrid structure with ∼1200% enhanced photoresponsivity, compared to a conventional flat graphene-only photodetector, and exceptional mechanical stretchability up to a 200% tensile strain. We achieve plasmonically enhanced photoresponsivity by integrating AuNPs with graphene. By crumpling the hybrid structure, we realize mechanical stretchability and further enhancement of the optical absorption by densification. We also demonstrate that our highly stretchable photodetector with enhanced photoresponsivity can be integrated on a contact lens and a spring structure. We believe that our stretchable, high performance graphene photodetector can find broad applications for conformable and flexible optical sensors and dynamic mechanical strain sensors.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Ren, S. J.; Charles, J.; Wang, X. C.; Nie, F. X.; Romero, C.; Neti, S.; Zheng, Y.; Hoenig, S.; Chen, C.; Cao, F.; Bonner, R.; Pearlman, H.
Corrosion testing of metals in contact with calcium chloride hexahydrate used for thermal energy storage Journal Article
In: MATERIALS AND CORROSION-WERKSTOFFE UND KORROSION, vol. 68, no. 10, pp. 1046-1056, 2017, ISSN: 0947-5117.
@article{WOS:000412167800003,
title = {Corrosion testing of metals in contact with calcium chloride hexahydrate
used for thermal energy storage},
author = {S. J. Ren and J. Charles and X. C. Wang and F. X. Nie and C. Romero and S. Neti and Y. Zheng and S. Hoenig and C. Chen and F. Cao and R. Bonner and H. Pearlman},
doi = {10.1002/maco.201709432},
issn = {0947-5117},
year = {2017},
date = {2017-10-01},
journal = {MATERIALS AND CORROSION-WERKSTOFFE UND KORROSION},
volume = {68},
number = {10},
pages = {1046-1056},
publisher = {WILEY-V C H VERLAG GMBH},
address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY},
abstract = {Thermal energy storage (TES) using a phase change material (PCM) has
been proposed as a supplemental cooling system to improve the
performance of power plant air-cooled condensers (ACCs). In this
proposed system, frozen PCM would remove heat from plant's condensing
steam during the day, which would melt the PCM. The PCM would be frozen
at night as its stored heat is rejected to the cooler atmosphere.
Calcium chloride hexahydrate (CaCl2 center dot 6H(2)O) is an attractive
material to serve as a PCM in this innovative system due to its
appropriate melting temperature, low price, and relatively high latent
heat of fusion. The corrosion of container materials is a major
challenge in using CaCl2 center dot 6H(2)O. Any material used needs to
survive constant exposure to the salt for several years to ensure a long
operational life for the system. In this study, the corrosion behavior
of four metals in contact with CaCl2 center dot 6H(2)O was
experimentally investigated. Three different temperature conditions and
two pH level conditions were considered under static metal exposure
conditions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
been proposed as a supplemental cooling system to improve the
performance of power plant air-cooled condensers (ACCs). In this
proposed system, frozen PCM would remove heat from plant's condensing
steam during the day, which would melt the PCM. The PCM would be frozen
at night as its stored heat is rejected to the cooler atmosphere.
Calcium chloride hexahydrate (CaCl2 center dot 6H(2)O) is an attractive
material to serve as a PCM in this innovative system due to its
appropriate melting temperature, low price, and relatively high latent
heat of fusion. The corrosion of container materials is a major
challenge in using CaCl2 center dot 6H(2)O. Any material used needs to
survive constant exposure to the salt for several years to ensure a long
operational life for the system. In this study, the corrosion behavior
of four metals in contact with CaCl2 center dot 6H(2)O was
experimentally investigated. Three different temperature conditions and
two pH level conditions were considered under static metal exposure
conditions.
Cao, Fangyu; Hoenig, Sean; Chen, Chien-hua
DROPWISE CONDENSATION ON CARBON STEEL SURFACE Inproceedings
In: PROCEEDINGS OF THE ASME INTERNATIONAL MECHANICAL ENGINEERING CONGRESS AND EXPOSITION, 2016, VOL. 8, Amer Soc Mech Engineers AMER SOC MECHANICAL ENGINEERS, THREE PARK AVENUE, NEW YORK, NY 10016-5990 USA, 2017, ISBN: 978-0-7918-5062-6, (ASME International Mechanical Engineering Congress and Exposition (IMECE2016), Phoenix, AZ, NOV 11-17, 2016).
@inproceedings{WOS:000400877900017,
title = {DROPWISE CONDENSATION ON CARBON STEEL SURFACE},
author = {Fangyu Cao and Sean Hoenig and Chien-hua Chen},
isbn = {978-0-7918-5062-6},
year = {2017},
date = {2017-01-01},
booktitle = {PROCEEDINGS OF THE ASME INTERNATIONAL MECHANICAL ENGINEERING CONGRESS
AND EXPOSITION, 2016, VOL. 8},
publisher = {AMER SOC MECHANICAL ENGINEERS},
address = {THREE PARK AVENUE, NEW YORK, NY 10016-5990 USA},
organization = {Amer Soc Mech Engineers},
abstract = {The increasing demand of heat dissipation in power plants has pushed the
limits of current two-phase thermal technologies such as heat pipes and
vapor chambers. One of the most obvious areas for thermal improvement is
centered on the high heat flux condensers including improved
evaporators, thermal interfaces, etc, with low cost materials and
surface treatment. Dropwise condensation has shown the ability to
increase condensation heat transfer coefficient by an order of magnitude
over conventional filmwise condensation. Current dropwise condensation
research is focused on Cu and other special metals, the cost of which
limits its application in the scale of commercial power plants.
Presented here is a general use of self-assembled monolayer coatings to
promote dropwise condensation on low-cost steel-based surfaces. Together
with inhibitors in the working fluid, the surface of condenser is
protected by hydrophobic coating, and the condensation heat transfer is
promoted on carbon steel surfaces.},
note = {ASME International Mechanical Engineering Congress and Exposition
(IMECE2016), Phoenix, AZ, NOV 11-17, 2016},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
limits of current two-phase thermal technologies such as heat pipes and
vapor chambers. One of the most obvious areas for thermal improvement is
centered on the high heat flux condensers including improved
evaporators, thermal interfaces, etc, with low cost materials and
surface treatment. Dropwise condensation has shown the ability to
increase condensation heat transfer coefficient by an order of magnitude
over conventional filmwise condensation. Current dropwise condensation
research is focused on Cu and other special metals, the cost of which
limits its application in the scale of commercial power plants.
Presented here is a general use of self-assembled monolayer coatings to
promote dropwise condensation on low-cost steel-based surfaces. Together
with inhibitors in the working fluid, the surface of condenser is
protected by hydrophobic coating, and the condensation heat transfer is
promoted on carbon steel surfaces.
Keleş, Ahmet; Zhao, Erhai; Liu, Vincent W
Effective theory of interacting fermions in shaken square optical lattices Journal Article
In: Physical Review A, vol. 95, no. 6, pp. 063619, 2017, ISSN: 2469-9926.
@article{PhysRevA.95.063619,
title = {Effective theory of interacting fermions in shaken square optical lattices},
author = {Ahmet Kele\c{s} and Erhai Zhao and Vincent W Liu},
url = {https://link.aps.org/doi/10.1103/PhysRevA.95.063619 http://link.aps.org/doi/10.1103/PhysRevA.95.063619},
doi = {10.1103/PhysRevA.95.063619},
issn = {2469-9926},
year = {2017},
date = {2017-06-01},
journal = {Physical Review A},
volume = {95},
number = {6},
pages = {063619},
publisher = {American Physical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Zou, Haiyuan; Zhao, Erhai; Liu, Vincent W
Frustrated Magnetism of Dipolar Molecules on a Square Optical Lattice: Prediction of a Quantum Paramagnetic Ground State Journal Article
In: Physical Review Letters, vol. 119, no. 5, pp. 050401, 2017, ISSN: 0031-9007.
@article{PhysRevLett.119.050401,
title = {Frustrated Magnetism of Dipolar Molecules on a Square Optical Lattice: Prediction of a Quantum Paramagnetic Ground State},
author = {Haiyuan Zou and Erhai Zhao and Vincent W Liu},
url = {https://link.aps.org/doi/10.1103/PhysRevLett.119.050401 http://link.aps.org/doi/10.1103/PhysRevLett.119.050401},
doi = {10.1103/PhysRevLett.119.050401},
issn = {0031-9007},
year = {2017},
date = {2017-07-01},
journal = {Physical Review Letters},
volume = {119},
number = {5},
pages = {050401},
publisher = {American Physical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Wang, Michael Cai; Leem, Juyoung; Kang, Pilgyu; Choi, Jonghyun; Knapp, Peter; Yong, Keong; Nam, SungWoo
Mechanical instability driven self-assembly and architecturing of 2D materials Journal Article
In: 2D Materials, vol. 4, no. 2, pp. 022002, 2017, ISSN: 2053-1583.
@article{Wang2017e,
title = {Mechanical instability driven self-assembly and architecturing of 2D materials},
author = {Michael Cai Wang and Juyoung Leem and Pilgyu Kang and Jonghyun Choi and Peter Knapp and Keong Yong and SungWoo Nam},
url = {http://stacks.iop.org/2053-1583/4/i=2/a=022002?key=crossref.f4723d0c820bc3cf2650ad83fec550c1},
doi = {10.1088/2053-1583/aa62e8},
issn = {2053-1583},
year = {2017},
date = {2017-03-01},
journal = {2D Materials},
volume = {4},
number = {2},
pages = {022002},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Guterding, Daniel; Jeschke, Harald O; Mazin, I I; Glasbrenner, J K; Bascones, E; Valentí, Roser
Nontrivial Role of Interlayer Cation States in Iron-Based Superconductors Journal Article
In: Physical Review Letters, vol. 118, no. 1, pp. 017204, 2017, ISSN: 0031-9007.
@article{Guterding2017_PRL_Nontrivial,
title = {Nontrivial Role of Interlayer Cation States in Iron-Based Superconductors},
author = {Daniel Guterding and Harald O Jeschke and I I Mazin and J K Glasbrenner and E Bascones and Roser Valent\'{i}},
url = {https://link.aps.org/doi/10.1103/PhysRevLett.118.017204},
doi = {10.1103/PhysRevLett.118.017204},
issn = {0031-9007},
year = {2017},
date = {2017-01-01},
journal = {Physical Review Letters},
volume = {118},
number = {1},
pages = {017204},
publisher = {American Physical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Oliver, Sean M; Beams, Ryan; Krylyuk, Sergiy; Kalish, Irina; Singh, Arunima K; Bruma, Alina; Tavazza, Francesca; Joshi, Jaydeep; Stone, Iris R; Stranick, Stephan J; Davydov, Albert V; Vora, Patrick M
The structural phases and vibrational properties of Mo 1−x W x Te 2 alloys Journal Article
In: 2D Materials, vol. 4, no. 4, pp. 045008, 2017, ISSN: 2053-1583.
@article{Oliver2017b,
title = {The structural phases and vibrational properties of Mo 1−x W x Te 2 alloys},
author = {Sean M Oliver and Ryan Beams and Sergiy Krylyuk and Irina Kalish and Arunima K Singh and Alina Bruma and Francesca Tavazza and Jaydeep Joshi and Iris R Stone and Stephan J Stranick and Albert V Davydov and Patrick M Vora},
url = {http://arxiv.org/abs/1703.10985%0Ahttp://dx.doi.org/10.1088/2053-1583/aa7a32 http://stacks.iop.org/2053-1583/4/i=4/a=045008?key=crossref.6ba8b9b9212ad2239ec721d728eec57f},
doi = {10.1088/2053-1583/aa7a32},
issn = {2053-1583},
year = {2017},
date = {2017-08-01},
journal = {2D Materials},
volume = {4},
number = {4},
pages = {045008},
publisher = {IOP Publishing},
abstract = {The structural polymorphism in transition metal dichalcogenides (TMDs) provides exciting opportunities for developing advanced electronics. For example, MoTe$_2$ crystallizes in the 2H semiconducting phase at ambient temperature and pressure, but transitions into the 1T$^backslashprime$ semimetallic phase at high temperatures. Alloying MoTe$_2$ with WTe$_2$ reduces the energy barrier between these two phases, while also allowing access to the T$_d$ Weyl semimetal phase. The MoWTe$_2$ alloy system is therefore promising for developing phase change memory technology. However, achieving this goal necessitates a detailed understanding of the phase composition in the MoTe$_2$-WTe$_2$ system. We combine polarization-resolved Raman spectroscopy with X-ray diffraction (XRD) and scanning transmission electron microscopy (STEM) to study MoWTe$_2$ alloys over the full compositional range x from 0 to 1. We identify Raman and XRD signatures characteristic of the 2H, 1T$^backslashprime$, and T$_d$ structural phases that agree with density-functional theory (DFT) calculations, and use them to identify phase fields in the MoTe$_2$-WTe$_2$ system, including single-phase 2H, 1T$^backslashprime$, and T$_d$ regions, as well as a two-phase 1T$^backslashprime$ + T$_d$ region. Disorder arising from compositional fluctuations in MoWTe$_2$ alloys breaks inversion and translational symmetry, leading to the activation of an infrared 1T$^backslashprime$-MoTe$_2$ mode and the enhancement of a double-resonance Raman process in 2H-MoWTe$_2$ alloys. Compositional fluctuations limit the phonon correlation length, which we estimate by fitting the observed asymmetric Raman lineshapes with a phonon confinement model. These observations reveal the important role of disorder in MoWTe$_2$ alloys, clarify the structural phase boundaries, and provide a foundation for future explorations of phase transitions and electronic phenomena in this system.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2015
Cao, Fangyu; Liu, Ying; Xu, Jiajun; He, Yadong; Hammouda, B.; Qiao, Rui; Yang, Bao
Probing Nanoscale Thermal Transport in Surfactant Solutions Journal Article
In: SCIENTIFIC REPORTS, vol. 5, 2015, ISSN: 2045-2322.
@article{WOS:000364037600001,
title = {Probing Nanoscale Thermal Transport in Surfactant Solutions},
author = {Fangyu Cao and Ying Liu and Jiajun Xu and Yadong He and B. Hammouda and Rui Qiao and Bao Yang},
doi = {10.1038/srep16040},
issn = {2045-2322},
year = {2015},
date = {2015-11-01},
journal = {SCIENTIFIC REPORTS},
volume = {5},
publisher = {NATURE PUBLISHING GROUP},
address = {MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND},
abstract = {Surfactant solutions typically feature tunable nanoscale, internal
structures. Although rarely utilized, they can be a powerful platform
for probing thermal transport in nanoscale domains and across interfaces
with nanometer-size radius. Here, we examine the structure and thermal
transport in solution of AOT (Dioctyl sodium sulfosuccinate) in n-octane
liquids using small-angle neutron scattering, thermal conductivity
measurements, and molecular dynamics simulations. We report the first
experimental observation of a minimum thermal conductivity occurring at
the critical micelle concentration (CMC): the thermal conductivity of
the surfactant solution decreases as AOT is added till the onset of
micellization but increases as more AOT is added. The decrease of
thermal conductivity with AOT loading in solutions in which AOT
molecules are dispersed as monomers suggests that even the interfaces
between individual oleophobic headgroup of AOT molecules and their
surrounding non-polar octane molecules can hinder heat transfer. The
increase of thermal conductivity with AOT loading after the onset of
micellization indicates that the thermal transport in the core of AOT
micelles and across the surfactant-oil interfaces, both of which span
only a few nanometers, are efficient.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
structures. Although rarely utilized, they can be a powerful platform
for probing thermal transport in nanoscale domains and across interfaces
with nanometer-size radius. Here, we examine the structure and thermal
transport in solution of AOT (Dioctyl sodium sulfosuccinate) in n-octane
liquids using small-angle neutron scattering, thermal conductivity
measurements, and molecular dynamics simulations. We report the first
experimental observation of a minimum thermal conductivity occurring at
the critical micelle concentration (CMC): the thermal conductivity of
the surfactant solution decreases as AOT is added till the onset of
micellization but increases as more AOT is added. The decrease of
thermal conductivity with AOT loading in solutions in which AOT
molecules are dispersed as monomers suggests that even the interfaces
between individual oleophobic headgroup of AOT molecules and their
surrounding non-polar octane molecules can hinder heat transfer. The
increase of thermal conductivity with AOT loading after the onset of
micellization indicates that the thermal transport in the core of AOT
micelles and across the surfactant-oil interfaces, both of which span
only a few nanometers, are efficient.