Topological Thermal Hall Effect of Magnons in Magnetic Skyrmion Lattice

TL;DR

This paper demonstrates the topological thermal Hall effect of magnons in a magnetic skyrmion lattice, revealing how bosonic excitations can exhibit topological transport phenomena similar to fermions.

Contribution

It provides experimental evidence of the topological thermal Hall effect of magnons in a skyrmion lattice, linking the effect to the Chern number of the lowest magnon band.

Findings

Detected a distinct thermal Hall signal in the skyrmion phase

Attributed the signal to the topological thermal Hall effect of magnons

Connected the effect to the Chern number of the magnon band

Abstract

Topological transports of fermions are governed by the Chern numbers of the energy bands lying below the Fermi energy. For bosons, e.g. phonons and magnons in a crystal, topological transport is dominated by the Chern number of the lowest energy band when the band gap is comparable to the thermal energy. Here, we demonstrate the presence of topological transport by bosonic magnons in a lattice of magnetic skyrmions - topological defects formed by a vortex-like texture of spins. We find a distinct thermal Hall signal in the magnetic skyrmion phase of an insulating polar magnet GaV4Se8, identified as the topological thermal Hall effect of magnons governed by the Chern number of the lowest energy band of the magnons in a triangular lattice of magnetic skyrmions. Our findings lay a foundation for studying topological phenomena of other bosonic excitations through thermal Hall probe.