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

J Phys Condens Matter. 2017 Apr 20;29(15):155601. doi: 10.1088/1361-648X/aa61e7. Epub 2017 Feb 21.

Abstract

Ferroelectric properties of cubic chiral magnet Cu2OSeO3 can emerge due to the spin noncollinearity induced by antiferromagnetic cantings. The 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 [Formula: see text]. 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, [Formula: see text] and [Formula: see text], can give contributions of the same order of magnitude into the electric polarization.