Theory of spin-orbit enhanced electric-field control of magnetism in multiferroic BiFeO3

TL;DR

This paper develops a microscopic theory demonstrating how spin-orbit coupling in BiFeO3 enables electric-field control of magnetism, allowing magnetic state manipulation without changing ferroelectric polarization, which could reduce energy dissipation.

Contribution

The paper introduces a novel microscopic model showing spin-orbit coupling's role in electric-field control of magnetism in BiFeO3, highlighting a new mechanism for device applications.

Findings

Spin-orbit coupling induces magnetic anisotropy in BiFeO3.

Electric field can switch magnetic states without poling ferroelectricity.

Potential for low-energy spintronic devices using insulator materials.

Abstract

We present a microscopic theory that shows the importance of spin-orbit coupling in perovskite compounds with heavy ions. In BiFeO3 (BFO) the spin-orbit coupling at the bismuth ion sites results in a special kind of magnetic anisotropy that is linear in the applied E-field. This interaction can convert the cycloid ground state into a homogeneous antiferromagnet, with a weak ferromagnetic moment whose orientation can be controlled by the E-field direction. Remarkably, the E-field control of magnetism occurs without poling the ferroelectric moment, providing a pathway for reduced energy dissipation in spin-based devices made of insulators.