Speaker: Dr. Xiaoqi Sun, University of Illinois at Urbana-Champaigny

Host: Prof. Yi Zhou, Institute of Physics, CAS

Time: 10:00 am, February 20th, 2023

Abstract: 

Recent experiments have observed unexpectedly large thermal Hall effects in insulating materials including the parent compounds of the high temperature superconducting cuprates, where the heat carriers have been identified to be acoustic phonons. We will analyze the magnitude of both intrinsic and extrinsic thermal Hall effects from acoustic phonons. While we predict that the intrinsic phonon thermal Hall effect can be large in certain nearly ferroelectric insulators [1], extrinsic mechanisms are generically more important in experiments [2]. We will discuss resonant skew scattering [2] with dynamical defects, which can be a fundamental ingredient for the large phonon thermal Hall effect in general materials.

Reference:

[1] JY Chen, SA Kivelson, XQ Sun, Phys. Rev. Lett. 124, 167601, 2020

[2] XQ Sun, JY Chen, SA Kivelson, Phys. Rev. B 106, 144111, 2022

Brief CV of Dr. Xiaoqi Sun:

Dr. Xiaoqi Sun is currently a Gordon and Betty Moore Postdoctoral Scholar at the Institute for Condensed Matter Theory in the University of Illinois at Urbana-Champaign. He completed his B.S. in physics at Tsinghua University, and his Ph.D. in physics at Stanford University. His current research interests involve topological phenomena out of equilibrium, dynamics and transport in quantum materials, and interdisciplinary studies at the intersection of many-body physics, machine learning and quantum information science.