First-principles investigation of the very large perpendicular magnetic anisotropy at Fe|MgO and Co|MgO interfaces

The perpendicular magnetic anisotropy (PMA) arising at the interface between ferromagnetic transition metals and metallic oxides was investigated via first-principles calculations. In this work very large values of PMA, up to 3 erg/cm(2), at Fe vertical bar 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(z2) orbitals hybridized with d(xz(yz)) orbitals with stronger spin-orbit coupling-induced splitting around the Fermi level for perpendicular magnetization orientation. Furthermore, it is shown that the PMA value weakens in the case of over- or underoxidation due to the fact that oxygen p(z) and transitionmetal d(z2) orbital overlap is strongly affected by disorder, in agreement with experimental observations in magnetic tunnel junctions.