SU(3) Topology of Magnon-Phonon Hybridization in 2D Antiferromagnets

TL;DR

This paper theoretically investigates the SU(3) topological properties of magnon-phonon hybrid excitations in 2D antiferromagnets, revealing nontrivial topology and skyrmion structures in momentum space.

Contribution

It introduces a continuum theory showing the SU(3) topology of magnon-phonon hybridization in 2D antiferromagnets, applicable beyond lattice specifics.

Findings

Identification of SU(3) topological structure in magnon-phonon bands

Skyrmion-like momentum space configuration

Proposed experimental detection via thermal Hall conductance

Abstract

Magnon-phonon hybrid excitations are studied theoretically in a two-dimensional antiferromagnet with an easy axis normal to the plane. We show that two magnon bands and one phonon band are intertwined by the magnetoelastic coupling through a nontrivial SU(3) topology, which can be intuitively perceived by identifying a skyrmion structure in the momentum space. We develop a continuum theory as the long-wavelength approximation to the tight-binding model, showing our results are insensitive to lattice details and generally applicable to two-dimensional antiferromagnets. The theoretical results can be probed by measuring the thermal Hall conductance as a function of the temperature and the magnetic field. We envision that the magnetoelastic coupling in antiferromagnets can be a promising venue in search of various topological excitations, which cannot be found in magnetic or elastic models alone.