"Enhanced Thermal Hall Effect in Nearly Ferroelectric Insulators"

Jing-Yuan Chen: Steven A. Kivelson and Xiao-Qi Sun; Physical Review Letters, 04/21/20.

Additional Authors: Steven A. Kivelson and Xiao-Qi Sun

Abstract:

In the context of recent experimental observations of an unexpectedly large thermal Hall conductivity, κH, in insulating La2CuO4 (LCO) and SrTiO3 (STO), we theoretically explore conditions under which acoustic phonons can give rise to such a large κH. Both the intrinsic and extrinsic contributions to κH are large in proportion to the dielectric constant, ε, and the “flexoelectric” coupling, F. While the intrinsic contribution is still orders of magnitude smaller than the observed effect, an extrinsic contribution proportional to the phonon mean-free path appears likely to account for the observations, at least in STO. We predict a larger intrinsic κH in certain insulating perovskites.