Thickness and Ferroelectric Polarization Influence on Film Magnetic Anisotropy across a Multiferroic Material Interface

The ferroelectric switching effect on perpendicular magnetic anisotropy is examined for the case of the BaTiO3/L10-CoFe interface through first-principles calculations of film magnetocrystalline anisotropy energy (MAE), both with the frozen-potential method and the second-order perturbation theory. The ferroelectric switching–MAE relationship is shown to have opposite trends for BaO- and TiO2-terminated interfaces because of the distinct orbital interaction mechanisms predominant in each termination configuration. The ferroelectric switching effect, changes in Fe–O bond lengths, and termination constitute three different contributors to MAE change, each with a different penetration depth into the CoFe film. The top surface CoFe atoms are shown to feature a high density of minority-spin 3dxz states, which could play a role in influencing the ferroelectric switching–MAE relationship in cases where the top surface undergoes modifications.