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

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 $|{\kappa }_{xy}/T|<1\times 10^{-4}$ $\mathrm{W}{\mathrm{m}}^{-1}{\mathrm{K}}^{-2}$. 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.