Speaker: Dr. Ilija Zeljkovic of Boston College
The kagome lattice of transition metal atoms provides an exciting platform to study the interplay of electronic correlations and band topology. AV3Sb5 (A=K, Rb, Cs) is a recently discovered class of kagome metals that does not exhibitresolvable magnetic order, and yet, surprisingly, shows a large anomalous Hall response and superconductivity. In this talk, I will discuss our experiments on AV3Sb5 materials using low-temperature spectroscopic imaging scanning tunneling microscopy. In CsV3Sb5, we discover a cascade of different symmetry-broken electronic states as a function of temperature. At a temperature far above the superconducting transition Tc ~ 2.5 K, we reveal a tri-directional charge order with a 2a0 period that breaks the translation symmetry of the lattice. As the system is cooled down towards Tc, we observe an additional breaking of the six-fold rotation symmetry, which persists through the superconducting transition. This rotation symmetry breaking is observed as the emergence of an additional 4a0 unidirectional charge order and strongly anisotropic scattering attributed to the orbital-selective renormalization of the Vanadium kagome bands. I will conclude by discussing the symmetry of the 2a0 CDW state in KV3Sb5 and its response to an externally applied magnetic field. Our experiments reveal a complex landscape of electronic states that can co-exist on a kagome lattice, and provide intriguing parallels to high-Tc superconductors and twisted bilayer graphene.
October 4, 2021, 03:00 – 04:00 PM Eastern Time (US and Canada)
Meeting ID: 950 9309 9839