https://gmu.zoom.us/j/98862070619?pwd=VkE4eTYyZDkxL2tQbkNrNm1TbzZiZz09
Title: Condense Matter Physics Seminar: Chirality-assisted vortex spin and toroidal moment in a triangular magnet, by Dr. Lei Ding of ORNL
Speaker: Dr. Lei Ding, Oak Ridge National Laboratory
Time: January 25, 2021 03:00 PM Eastern Time (US and Canada)
Join Zoom Meeting:
https://gmu.zoom.us/j/96920316926?pwd=SjZybGp1N2c2QjBsWFVXcVpOMFc0dz09
Abstract:
A toroidal dipole moment appears independent of the electric and magnetic dipole moment in the multipole expansion of electrodynamics. It arises naturally from vortex-like arrangements of spins. Observing and controlling spontaneous long-range orders of toroidal moments are highly promising for spintronics but remain challenging. In this talk, I present that a vortex-like spin configuration harboring a staggered arrangement of toroidal moments, a ferritoroidal state, is realized in a chiral triangular-lattice magnet BaCoSiO4. Upon applying a magnetic field, we observe multi-stair toroidal transitions correlating directly with metamagnetic transitions. We establish a first-principles microscopic Hamiltonian that explains both the formation of toroidal states and the metamagnetic toroidal transition as a combined effect of the magnetic frustration and the Dzyaloshinskii-Moriya interactions allowed by the crystallographic chirality.
Brief biography:
Lei Ding received his PhD degree from the Université Grenoble Alpes & Institut Néel, France, in Physics in 2016. Prior to joining the ORNL as a postdoc researcher, he was the Rutherford International fellow at the ISIS neutron and muon source, UK. His research interest lies in condensed matter physics with a particular focus on the study of emergent orders and excitations from the interplay between spin, charge, orbital, topology and lattice in novel materials including frustrated magnets, multiferroics and magnetic topological insulators.