Chiral magnon-polaron edge states in Heisenberg-Kitaev magnets

TL;DR

This paper explores how magnons and chiral phonons interact in two-dimensional non-centrosymmetric magnets, revealing topological magnon-polaron edge states with potential for angular momentum transfer.

Contribution

It introduces a general form of magnetoelastic coupling in non-centrosymmetric 2D magnets and demonstrates the emergence of topological magnon-polaron edge states in the Heisenberg-Kitaev-$\Gamma$ model.

Findings

Magnon-phonon coupling depends on lattice symmetry and anisotropic exchange interactions.

Chiral phonons induce topological edge states in magnon spectra.

Circular polarization of magnon-polaron edge states is demonstrated.

Abstract

The interplay of spin and lattice fluctuations in two-dimensional magnets without inversion symmetry is investigated. We find a general form for the magnetoelastic coupling between magnons and existing chiral phonons based on the symmetries of the crystalline lattice. We show that in hexagonal lattices, the coupling of magnons and chiral phonons derives from an anisotropic exchange spin model containing topological phases of magnons. Using the Heisenberg-Kitaev-$\Gamma$ model, we show how magnon-polaron edge states with circular polarization arise from this interaction. Our findings exploit the polarization degrees of freedom in spin-lattice systems, thus setting the ground for the transfer of angular momentum between chiral phonons and magnons.