Theory of magnetic switching of ferroelectricity in spiral magnets

TL;DR

This paper develops a microscopic theory explaining how magnetic fields induce switching of electric polarization in spiral multiferroic materials, supported by simulations of phase diagrams and magnetic transitions.

Contribution

It introduces a detailed spin model that captures magnetic switching mechanisms in spiral multiferroics like TbMnO3 and DyMnO3, linking microscopic interactions to macroscopic polarization changes.

Findings

Reproduces phase diagrams under magnetic fields using Monte-Carlo simulations.

Identifies competition among Dzyaloshinskii-Moriya interaction, spin anisotropy, and exchange as key to polarization switching.

Explains magnetic transition mechanisms leading to polarization reorientation or disappearance.

Abstract

We propose a microscopic theory for magnetic switching of electric polarization (P) in the spin-spiral multiferroics by taking TbMnO3 and DyMnO3 as examples. We reproduce their phase diagrams under a magnetic field H_ex by Monte-Carlo simulation of an accurate spin model and reveal that competition among the Dzyaloshinskii-Moriya interaction, spin anisotropy, and spin exchange is controlled by the applied H_ex, resulting in magnetic transitions accompanied by reorientation or vanishing of P. We also discuss the relevance of the proposed mechanisms to many other multiferroics such as LiCu2O2, MnWO4, and Ni3V2O4