Perpendicular magnetization of CoFeGe alloy films induced by MgO interface*

The perpendicular magnetization of CoFeGe alloy films was achieved in the structures of CoFeGe/MgO with the perpendicular magnetic anisotropy energy density ($K_{u})$ of $\sim $ 1 x 10$^{6 }$erg/cm$^{3}$. The CoFeGe thickness dependence of $K_{u}$ was investigated, indicating that the perpendicular anisotropy of CoFeGe is contributed by the interfacial anisotropy between CoFeGe and MgO. High-resolution transmission electron microscope images clearly show formation of bcc crystalline structure of CoFeGe well lattice matched with the (100)-oriented MgO barrier. Gilbert damping constant for the films was evaluated by using ferromagnetic resonance measurement.