Ferroelectricity in spiral magnets

TL;DR

This paper presents a phenomenological theory explaining how spiral magnetic structures induce ferroelectricity, detailing polarization behavior, temperature and field dependence, and novel phenomena like charge in vortices.

Contribution

It introduces a simple model describing electric polarization in incommensurate magnetic states, including domain wall and vortex effects, advancing understanding of multiferroic materials.

Findings

Electric polarization depends on magnetic state and external conditions.

Domain walls can induce electric polarization.

Magnetic vortices carry electric charge.

Abstract

It was recently observed that materials showing most striking multiferroic phenomena are frustrated spin-density-wave magnets. We present a simple phenomenological theory, which describes the orientation of the induced electric polarization for various incommensurate magnetic states, its dependence on temperature and magnetic field, and anomalies of dielectric susceptibility at magnetic transitions. We show that electric polarization can be induced at domain walls and that magnetic vortices carry electric charge.