Layer-resolved magnetic moments in N-surfactant assisted FeNi ordered alloy thin films

We investigated structural and magnetic properties of FeNi ordered alloy thin films grown by nitrogen-surfactant assisted process using scanning tunneling microscopy and soft-X-ray absorption spectroscopy/magnetic circular dichroism. With the help of structurally controlled surface and interface by the N surfactant effect, the results successfully provide the layer-resolved spin magnetic moments of the Fe layer. Furthermore, the critical role of the topmost layer on the magnetic anisotropy is identified from a thickness dependence of the Fe orbital magnetic moment; the out-of-plane magnetization emerges when the Fe-N bonds, which favor the in-plane magnetization, break and the Ni-N bonds form in the NiN topmost layer.