Anomalous Nernst and Righi-Leduc effects in Mn$_{3}$Sn: Berry curvature and entropy flow

TL;DR

This study investigates the anomalous Nernst and Righi-Leduc effects in Mn$_{3}$Sn, revealing Berry curvature's role in thermal and electrical responses at room temperature, with implications for understanding topological effects in antiferromagnets.

Contribution

It demonstrates that Berry curvature induces measurable off-diagonal thermal and thermoelectric effects in Mn$_{3}$Sn, with results consistent with Fermi surface quasiparticles and no inelastic scattering influence.

Findings

Berry curvature causes detectable off-diagonal thermal and thermoelectric signals.

Thermal and electrical Hall conductivities follow the Wiedemann-Franz law.

The anomalous Lorenz number remains close to the Sommerfeld number across temperatures.

Abstract

We present a study of electric, thermal and thermoelectric response in noncollinear antiferromagnet Mn$_{3}$Sn, which hosts a large Anomalous Hall Effect (AHE). Berry curvature generates off-diagonal thermal(Righi-Leduc) and thermoelectric(Nernst) signals, which are detectable at room temperature and invertible with a small magnetic field. The thermal and electrical Hall conductivities respect the Wiedemann-Franz law, implying that the transverse currents induced by Berry curvature are carried by Fermi surface quasi-particles. In contrast to conventional ferromagnets, the anomalous Lorenz number remains close to the Sommerfeld number over the whole temperature range of study, excluding any contribution by inelastic scattering and pointing to Berry curvature as the unique source of AHE. The anomalous off-diagonal thermo-electric and Hall conductivities are strongly temperature-dependent and their ratio is close to k$_{B}$/e.