Chirality-induced magnon transport in AA-stacked bilayer honeycomb chiral magnets

TL;DR

This paper investigates how chirality influences magnon transport in AA-stacked bilayer honeycomb chiral magnets, revealing edge states and Hall effects, with distinct behaviors depending on magnetic coupling type.

Contribution

It introduces the study of magnon transport phenomena in bilayer honeycomb chiral magnets, highlighting the effects of ferromagnetic and antiferromagnetic couplings on topological magnon properties.

Findings

Chirality induces gaps and protected edge states in magnon spectra.

Ferromagnetic layers show consistent thermal Hall and Nernst conductivities.

Antiferromagnetic layers exhibit sign reversal in conductivities with magnetic field reversal.

Abstract

In this Letter, we study the magnetic transport in AA-stacked bilayer honeycomb chiral magnets coupled either ferromagnetically or antiferromagnetically. For both couplings, we observe chirality-induced gaps, chiral protected edge states, magnon Hall and magnon spin Nernst effects of magnetic spin excitations. For ferromagnetically coupled layers, thermal Hall and spin Nernst conductivities do not change sign as function of magnetic field or temperature similar to single-layer honeycomb ferromagnetic insulator. In contrast, for antiferromagnetically coupled layers, we observe a sign change in the thermal Hall and spin Nernst conductivities as the magnetic field is reversed. We discuss possible experimental accessible honeycomb bilayer quantum materials in which these effects can be observed.