Magnon Landau Levels and Spin Responses in Antiferromagnets

TL;DR

This paper explores how inhomogeneous Dzyaloshinskii-Moriya interactions create Landau levels in antiferromagnetic insulators, revealing relativistic physics and topological magnon responses.

Contribution

It introduces a model of AFM topological insulator of magnons with Landau levels induced by gauge fields from Dzyaloshinskii-Moriya interaction gradients, highlighting relativistic effects.

Findings

Landau levels exhibit relativistic Klein-Gordon physics.

Magnon Landau levels lead to a spin Nernst response.

Rich topological magnon excitations are present in AFM insulators.

Abstract

We study gauge fields produced by gradients of the Dzyaloshinskii-Moriya interaction and propose a model of AFM topological insulator of magnons. In the long wavelength limit, the Landau levels induced by the inhomogeneous Dzyaloshinskii-Moriya interaction exhibit relativistic physics described by the Klein-Gordon equation. The spin Nernst response due to the formation of magnonic Landau levels is compared to similar topological responses in skyrmion and vortex-antivortex crystal phases of AFM insulators. Our studies show that AFM insulators exhibit rich physics associated with topological magnon excitations.