Topological spin waves in the atomic-scale magnetic skyrmion crystal

TL;DR

This paper explores the topological properties of spin waves in a skyrmion crystal, revealing non-trivial band topology and chiral edge modes that are robust against backscattering, highlighting emergent topological phases in magnetic systems.

Contribution

It demonstrates the existence of topologically non-trivial spin wave bands and chiral edge states in a skyrmion crystal, a novel finding in magnetic topological phases.

Findings

Spin wave bands have finite Berry curvature and non-zero Chern numbers.

Edge spin-waves are chiral and immune to backscattering.

Topological phases can occur in self-generated emergent superlattices.

Abstract

We study the spin waves of the triangular skyrmion crystal that emerges in a two dimensional spin lattice model as a result of the competition between Heisenberg exchange, Dzyalonshinkii-Moriya interactions, Zeeman coupling and uniaxial anisotropy. The calculated spin wave bands have a finite Berry curvature that, in some cases, leads to non-zero Chern numbers, making this system topologically distinct from conventional magnonic systems. We compute the edge spin-waves, expected from the bulk-boundary correspondence principle, and show that they are chiral, which makes them immune to elastic backscattering. Our results illustrate how topological phases can occur in self-generated emergent superlattices at the mesoscale.