The magnetoelectric coupling in the multiferroic compound LiCu2O2

TL;DR

This paper develops a phenomenological model to understand the magnetoelectric coupling in LiCu2O2, explaining experimental phenomena like polarization flop and electromagnon excitations through a group-theoretical approach.

Contribution

It introduces a new multi-order parameter model that accounts for the coupling mechanisms in LiCu2O2, explaining experimental observations and predicting electromagnon behavior.

Findings

Coupling involving inter-chain magnetic structure and ferroelectricity is essential.

The model explains the electric polarization flop under magnetic fields.

Electromagnon peaks are predicted to be field-dependent.

Abstract

We investigate the possible types of coupling between ferroelectricity and magnetism for the zig-zag spin chain multiferroic LiCu2O2 compound. We construct a multi-order parameter phenomenological model for the material based on a group theoretical analysis. From our calculation we conclude that a coupling involving the inter-chain magnetic structure and ferroelectricity is necessary to understand the experimental results of Park et.al. Our proposed model is able to account for the electric polarization flop in the presence of an externally applied magnetic field. Furthermore, based on our theoretical model we can make specific selection rule predictions about electromagnon excitations present in the LiCu2O2 system. We also predict that the electromagnon peaks measured in an ac-conductivity measurement are field dependent.