Ferroelectricity Induced by Proper-Screw Type Magnetic Order

Abstract

A novel type of magnetic origin of ferroelectric polarization is proposed. In crystals with triclinic, monoclinic, or trigonal (rhombohedral) symmetries, the proper screw type of magnetic ordering can induce ferroelectricity through the variation in the metal–ligand hybridization with spin–orbit coupling. The ferroelectric polarization in delafossite compounds Cu(Fe,Al)O 2 is successfully explained by the mechanism. The relation between the polarization direction and the magnetic modulation vector is also predicted.