Antiferromagnetic spin cantings as a driving force of ferroelectricity in multiferroic Cu2OSeO3

TL;DR

This paper explores how antiferromagnetic spin cantings, caused by Dzyaloshinskii-Moriya interactions, induce ferroelectricity in the multiferroic material Cu2OSeO3, providing a microscopic theoretical framework for this phenomenon.

Contribution

It introduces a new microscopic theory linking antiferromagnetic cantings to ferroelectricity in Cu2OSeO3, including an expression for local electric polarization with magnetization gradients.

Findings

Antiferromagnetic cantings induce ferroelectricity in Cu2OSeO3.

Both scalar and vector spin products contribute to electric polarization.

The theory accounts for crystal anisotropy effects on polarization.

Abstract

Ferroelectric properties of cubic chiral magnet Cu2OSeO3 can emerge due to the spin noncollinearity induced by antiferromagnetic cantings. These cantings are the result of the Dzyaloshinskii-Moriya interaction and in many ways similar to the ferromagnetic cantings in weak ferromagnets. An expression for the local electric polarization is derived, including terms with gradients of magnetization M(r). When averaged over the crystal the electric polarization has a non-vanishing part associated with the anisotropy of the crystal point group 23. In the framework of the microscopic theory, it is shown that both scalar and vector products of spins, (s1 . s2) and [s1 x s2], can give contributions of the same order in the electric polarization.