Anomalous magnon Nernst effect of topological magnonic materials

TL;DR

This paper investigates the anomalous magnon Nernst effect in topological magnonic materials, revealing how thermal gradients induce transverse magnon currents and predicting temperature-induced sign reversals.

Contribution

It introduces the concept of the anomalous magnon Nernst effect in topological magnonic systems and analyzes its dependence on Berry curvature and temperature.

Findings

Transverse magnon currents are generated by in-plane thermal gradients.

The anomalous magnon Nernst coefficient's sign depends on Berry curvature distribution.

A temperature-induced sign reversal of the effect is predicted.

Abstract

The magnon transport driven by thermal gradient in a perpendicularly magnetized honeycomb lattice is studied. The system with the nearest-neighbor pseudodipolar interaction and the next-nearest-neighbor Dzyaloshinskii-Moriya interaction (DMI) has various topologically nontrivial phases. When an in-plane thermal gradient is applied, a transverse in-plane magnon current is generated. This phenomenon is termed as the anomalous magnon Nernst effect that closely resembles the anomalous Nernst effect for an electronic system. The anomalous magnon Nernst coefficient and its sign are determined by the magnon Berry curvatures distribution in the momentum space and magnon populations in the magnon bands. We predict a temperature-induced sign reversal in anomalous magnon Nernst effect under certain conditions.