Chiral phonons induced from spin dynamics via magnetoelastic anisotropy

TL;DR

This paper introduces a mechanism for generating chiral phonon-like excitations through magnetoelastic couplings in certain magnetic systems, revealing their topological properties and potential for tunable spintronic and phononic applications.

Contribution

It demonstrates how bond-dependent magnetoelastic interactions can produce chiral phonons without external magnetic fields, linking lattice symmetry to topological phonon states.

Findings

Chiral phonons can be induced via magnetoelastic couplings without out-of-plane magnetization.

The system maps to topological class D phonons, showing tunable chirality with magnetic fields.

Phonon magnetization and thermal Hall conductivity are proposed as experimental probes.

Abstract

We propose a mechanism to obtain chiral phonon-like excitations from the bond-dependent magnetoelastic couplings in the absence of out-of-plane magnetization and magnetic fields. By mapping the hybrid excitation to its phononic analog, we reveal the impact of the lattice symmetry on the origin of the chirality. In the example of a triangular lattice ferromagnet, we recognize that the system is equivalent to the class D of topological phonons, and show the tunable chirality and topology by an in-plane magnetic field. As a possible experimental probe, we evaluate the phonon magnetization and planar thermal Hall conductivity. Our study gives a new perspective on tunable topological and chiral excitations beyond the Raman spin-lattice coupling, suggesting possible applications of spintronics and phononics in various anisotropic magnets and/or Kitaev materials.