General Microscopic Model of Magnetoelastic Coupling from First-Principles

TL;DR

This paper introduces a first-principles microscopic model for magnetoelastic coupling, revealing significant contributions to electric polarization in multiferroics, with broad applicability to related phenomena.

Contribution

The work develops a general microscopic model from density functional theory to describe magnetoelastic coupling and uncovers a dominant lattice deformation contribution to polarization.

Findings

Lattice deformation significantly contributes to polarization in BiFeO3.

The model reveals a previously unexpected magnetoelastic effect on electric polarization.

The approach can be applied to other magnetoelastic phenomena.

Abstract

Magnetoelastic coupling, i.e., the change of crystal lattice induced by a spin order, is not only scientifically interesting, but also technically important. In this work, we propose a general microscopic model from first-principles calculations to describe the magnetoelastic coupling and provide a way to construct the microscopic model from density functional theory calculations. Based on this model, we reveal that there exists a previously unexpected contribution to the electric polarization induced by the spin-order in multiferroics due to the combined effects of magnetoelastic coupling and piezoelectric effect. Interestingly and surprisingly, we find that this lattice deformation contribution to the polarization is even larger than that from the pure electronic and ion-displacement contributions in BiFeO3. This model of magnetoelastic coupling can be generally applied to investigate the other magnetoelastic phenomena.