Extrinsic magnetoelectric effect at the BaTiO3/Ni interface

Abstract

We theoretically investigate the interfacial magnetoelectric effect in the BaTiO3/Ni heterostructure. We find that magnetoelectric coupling, specifically, the dependence of the magnetic moment of Ni on the polarization direction, primarily stems from the flow of the screening charge from Ni into BaTiO3 with a minor contribution coming from interfacial chemical bonding. The estimated change in the magnetic moment from screening with respect to bulk Ni is as high as ∼7%, which is a significant modulation. We also examine the effects of interfacial oxidation on the electronic structures and the strength of magnetoelectric coupling in the BaTiO3/NiO/Ni structure. We find an enhancement of the interfacial bonding contribution, making it unfavorable for interfacial magnetoelectric modulation. In addition, we consider the effect of the Ni magnetic domain wall on interfacial coupling and find it to be negligible to the interfacial magnetoelectric effect.