Symmetry Analysis of Magnetoelectric Coupling Effect in All Point Groups

TL;DR

This paper uses symmetry analysis and Landau theory to explore magnetoelectric coupling in all point groups, explaining known multiferroics, predicting new candidates, and revealing novel polarization mechanisms and vortex states.

Contribution

It provides a comprehensive symmetry-based framework for understanding and predicting magnetoelectric effects in multiferroics, including new polarization sources and vortex phenomena.

Findings

Explains ferroelectric polarization in known type-II multiferroics.

Predicts 12 new multiferroic candidates with high magnetic transition temperatures.

Identifies collinear spin-sinusoidal textures as a source of ferroelectricity.

Abstract

Symmetry analysis provides crucial insights into the magnetoelectric coupling effect in type-II multiferroics. In this Letter, we comprehensively investigate couplings between electric polarization and inhomogeneous magnetization across all 32 crystallographic point groups using a phenomenological Landau theory. Our theory successfully explains the ferroelectric polarizations in all known type-II multiferroics characterized by incommensurate magnetic orders. In addition, we predict 12 promising type-II multiferroic candidates with the highest magnetic transition temperature of 84 K through systematic screening of MAGNDATA database. Furthermore, we find that the collinear spin-sinusoidal texture emerges as a previously unrecognized source of ferroelectric polarization. We also demonstrate that topological ferroelectric vortex states can be induced by ferromagnetic vortex configurations in uniaxial point groups, opening a route to realizing coexisting multiple-vortex states in multiferroics.