Enhancement in the interfacial perpendicular magnetic anisotropy and the voltage-controlled magnetic anisotropy by heavy metal doping at the Fe/MgO interface

A surface magnetoelectric effect is revealed by density-functional calculations that are applied to ferromagnetic Fe(001), Ni(001) and Co(0001) films in the presence of external electric field. The effect originates from spin-dependent screening of the electric field which leads to notable changes in the surface magnetization and the surface magnetocrystalline anisotropy. These results are of considerable interest in the area of electrically-controlled magnetism and magnetoelectric phenomena.

The perpendicular magnetic anisotropy (PMA) arising at the interface between ferromagnetic transition metals and metallic oxides are investigated via first-principles calculations. In this work very large values of PMA up to 3 erg/cm\(^2\) at Fe\(|\)MgO interfaces are reported in agreement with recent experiments. The origin of PMA is attributed to overlap between O-\(p_z\) and transition metal \(d_{z^2}\) orbitals hybridized with \(d_{xz(yz)}\) orbitals with stronger spin-orbit coupling induced splitting around the Fermi level for perpendicular magnetization orientation. Furthemore, it is shown that the PMA value weakens in case of over- or underoxidation when oxygen \(p_z\) and transition metal \(d_{z^2}\) orbitals overlap is strongly affected by disorder, in agreement with experimental observations in magnetic tunnel junctions.