Rotational motion of magnon and thermal Hall effect

TL;DR

This paper explores how Berry curvature influences magnon orbital motions, leading to thermal Hall effects and corrections in thermal transport, with applications to thin-film ferromagnets.

Contribution

It introduces a theoretical framework for magnon orbital motions caused by Berry curvature and applies it to magnetostatic spin waves in thin films.

Findings

Magnon wavepackets exhibit self-rotation and boundary motion due to Berry curvature.

The magnon edge current induces a thermal Hall effect.

Derived expressions for Berry curvature in thin-film ferromagnets.

Abstract

Due to the Berry curvature in momentum space, the magnon wavepacket undergoes two types of orbital motions in analogy with the electron system: the self-rotation motion and a motion along the boundary of the sample (edge current). The magnon edge current causes the thermal Hall effect, and these orbital motions give corrections to the thermal transport coefficients. We also apply our theory to the magnetostatic spin wave in a thin-film ferromagnet, and derive expression for the Berry curvature.