Anomalies in the thermal conductivity of honeycomb antiferromagnet MnPS$_{3}$

TL;DR

This study investigates thermal transport anomalies in the 2D honeycomb antiferromagnet MnPS₃, revealing sign reversals in thermal Hall conductivity at low temperatures linked to magnon Berry curvature redistribution.

Contribution

It uncovers low-temperature thermal Hall conductivity sign reversals in MnPS₃, highlighting the role of magnon Berry curvature redistribution, and demonstrates the effectiveness of thermal Hall measurements in magnetic insulators.

Findings

Thermal Hall conductivity shows sign reversals below 2 K.

Field dependence of thermal Hall conductivity exhibits anomalies within the spin-flop phase.

Berry curvature redistribution in magnon bands causes observed anomalies.

Abstract

Intrinsic two-dimensional magnets serve as a good platform to explore collective, charge-neutral and low-energy excitations. Distinguishing the crucial role of them in experimental aspect remains a challenge for decades. Here, we study the thermal transport in honeycomb antiferromagnet MnPS$_{3}$ with $T_N$=78 K down to very low temperatures (<0.01$T_N$). At high temperatures (>0.1$T_N$), the field dependence of the thermal Hall conductivity exhibits a linear phonon Hall effect and a peak associated with the spin-flop transition due to a strong spin-lattice coupling, well reproducing the previous report (Phys. Rev. B 110, 165147 (2024)). Notably, below 2 K, we find that the field dependence of the thermal Hall conductivity exhibits sign reversals within the spin-flop phase, at which the field dependence of the longitudinal thermal conductivity also shows multiple valleys. We suggest that these anomalies are caused by the redistribution of Berry curvature in magnon bands, demonstrating the superior performance of the thermal Hall measurements to detect the Berry curvature distributions in magnetic insulators.