High-resolution measurements of thermal conductivity matrix and search for thermal Hall effect in La 2 CuO 4

We investigated the longitudinal thermal conductivity κ xx and thermal Hall conductivity κ 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 | κ xy / T | < 1 × 10 − 4 Wm − 1 K − 2 . The longitudinal thermal conductivity κ xx / T agrees well with previous reports, in both its magnitude and T dependence. Both κ xx and κ xy were measured using the field-swept protocol. To achieve high resolution, we carefully took into account relaxation effects after each step-increase in H . At low T , we find a weak linear decrease in κ xx / T vs. H , as well as weak hystereses near the metamagnetic transitions of the spins.