Tunable Perpendicular Magnetic Anisotropy in Multiferroic Oxides

Here we present design rules to realize electric-field control of perpendicular magnetic anisotropy (PMA) utilizing hybrid improper ferroelectricity by scaffolding simple perovskite oxides into ultrashort period superlattices, (ABO₃)₁/(A'BO₃)₁, and in multiferroic AA'BB'O₆ double perovskites. The study validates the strategy using first-principles calculations and a single-ion-anisotropy model. We show a change of the magnetic anisotropy from the in-plane to out-of-plane direction occurs in (BiFeO₃)₁/(LaFeO₃)₁ and a 50% decrease of the magnetization along the out-of-plane direction occurs in LaYNiMnO₆ when a polar-to-nonpolar phase transition is activated with strain. The origin of the PMA control is due to the structural-tunable competitions among the t_2g and e_g orbital interactions on the magnetic ions arising from relativistic spin-orbital interactions that are susceptible to changes in the oxygen octahedral tilts with the transition. Our results allow us to search rapidly for other promising multiferroics materials with voltage-controlled magnetic anisotropy for applications in low-energy information storage and logic devices.