Magnetoelectricity of domain walls of rare-earth iron garnets

Abstract

We investigate a type of magnetoelectric effect in rare-earth iron garnets related to the presence of domain walls of the iron subsystem. The lack of space inversion in the dodecahedral rare-earth ion environments allows ferroelectric ordering in these materials. Electric polarization is absent in single-domain samples due to the antiferroelectricity of the electric-dipole structure. We show that the magnetic domain walls of the iron subsystem generate an effective inhomogeneous magnetic field arising from the rare-earth iron exchange interaction, which leads to emergence of electric polarization. A hallmark of this effect is that magnetoelectricity is independent of the type of magnetic domain walls. In contrast to the accepted concepts, we argue that the electric polarization in rare-earth iron garnets also occurs in the vicinity of Bloch magnetic walls. Magnetoelectric properties are inherent to rare-earth iron garnets in the presence of magnetic domain structure in any temperature range. Rare-earth iron garnets refer to multiferroics with $d$ and $f$ interacting subsystems.