Electric-Field Induced Spin Wave Nonreciprocity in Noncoplanar Magnets

TL;DR

This paper demonstrates that electric fields can induce nonreciprocal spin wave dispersion in certain noncoplanar magnetic insulators through a nonlinear magnetoelectric effect, without altering the magnetic ground state.

Contribution

It identifies symmetry conditions for electric-field-induced nonreciprocity and provides theoretical models for specific noncoplanar magnets showing this phenomenon.

Findings

Electric field controls nonreciprocity magnitude and direction.

Symmetry analysis constrains which magnets exhibit this effect.

Theoretical models confirm the effect in a hexagonal lattice antiferromagnet.

Abstract

We show that an electric field can induce nonreciprocal spin wave dispersion in magnetic insulators with negligible spin-orbit coupling. The electric field controls the direction and magnitude of nonreciprocity through a nonlinear magnetoelectric effect without switching the magnetic ground state. By deriving spin space group symmetry constraints, we find only a subset of noncoplanar magnets exhibits this property, and identify a few candidates. For the example of hexagonal lattice tetrahedral antiferromagnet, our effective field theory analysis and microscopic model calculation yield results that are fully consistent with the symmetry analysis.