Microwave magnetochiral effect in Cu2OSeO3

TL;DR

This paper predicts a giant microwave magnetochiral effect in Cu2OSeO3 due to coupled magnetic and electric excitations, leading to significant directional microwave absorption differences.

Contribution

It introduces a theoretical model showing how resonant magnetic and electric excitations in Cu2OSeO3 produce large magnetochiral dichroism at microwave frequencies.

Findings

Microwave absorption varies by up to 30% with propagation direction.

Coupling of magnetic and electric excitations enables giant dichroism.

The effect occurs at gigahertz frequencies in a multiferroic chiral magnet.

Abstract

We theoretically find that in a multiferroic chiral magnet Cu2OSeO3, resonant magnetic excitations are coupled to collective oscillation of electric polarization, and thereby attain simultaneous activity to ac magnetic field and ac electric field. Because of interference between these magnetic and electric activation processes, this material hosts gigantic magnetochiral dichroism on microwaves, that is, the directional dichroism at gigahertz frequencies in Faraday geometry. The absorption intensity of microwave differs by as much as 30% depending on whether its propagation direction is parallel or antiparallel to the external magnetic field.