High-resolution Measurements of Thermal Conductivity Matrix and Search for Thermal Hall Effect in La$_2$CuO$_4$

TL;DR

This study measured thermal conductivities in La$_2$CuO$_4$ at low temperatures and high magnetic fields, finding no detectable thermal Hall effect and confirming known longitudinal thermal behavior.

Contribution

The paper provides high-resolution measurements of thermal conductivity in La$_2$CuO$_4$, establishing an upper bound for the thermal Hall effect and analyzing magnetic field effects on thermal transport.

Findings

No detectable thermal Hall signal within measurement bounds

Longitudinal thermal conductivity matches previous results

Observed linear decrease of $rac{}{T}$ with magnetic field at low T

Abstract

We investigated the longitudinal thermal conductivity $\kappa_{xx}$ and thermal hall conductivity $\kappa_{xy}$ in La$_2$CuO$_4$ at temperatures $T$ between 2 and 20 K in magnetic fields $H$ up to 10 T. Within the temperature and field intervals studied, we do not resolve any thermal Hall signal with a conservative upper bound of $|\kappa_{xy}/T| <1\times10^{-4}$ ${\rm Wm^{-1}K^{-2}}$. The longitudinal thermal conductivity $\kappa_{xx}/T$ agrees well with previous studies, in both magnitude and $T$ dependence. In both channels, we performed measurements using the field-sweep protocol. To achieve high resolution, we carefully took into account relaxation effects after each step-increase in $H$. At low $T$, we find a linear decrease in $\kappa/T$ vs. $H$, as well as weak hysteresis near the meta-magnetic transition of the spin degrees.