Weak ferromagnetism and magnetoelectric coupling in bismuth ferrite

TL;DR

This paper investigates the magnetoelectric coupling in BiFeO3 using density functional theory, revealing weak ferromagnetism and discussing the potential for electric-field-induced magnetization reversal.

Contribution

It provides a detailed theoretical analysis of the coupling mechanisms in BiFeO3 and outlines conditions for electric-field-controlled magnetization switching.

Findings

Weak ferromagnetism of Dzyaloshinskii-Moriya type identified

Coupling between magnetization and structural distortions analyzed

Electric-field-induced magnetization reversal is unlikely but theoretically possible

Abstract

We analyze the coupling between the ferroelectric and magnetic order parameters in the magnetoelectric multiferroic BiFeO_3 using density functional theory within the local spin density approximation and the LSDA+U method. We show that weak ferromagnetism of the Dzyaloshinskii-Moriya type occurs in this material, and we analyze the coupling between the resulting magnetization and the structural distortions. We explore the possibility of electric-field-induced magnetization reversal and show that, although it is unlikely to be realized in BiFeO_3, it is not in general impossible. Finally we outline the conditions that must be fulfilled to achieve switching of the magnetization using an electric field.