The modulating effect of nitrogen doping on perpendicular magnetic anisotropy of CoFe/MgO thin films

We propose a method that manipulates the magnetic anisotropy of CoFe/MgO thin films by doping nitrogen (N) into CoFe. First-principle simulations are performed to investigate the magnetic anisotropy energy (MAE) and electronic structures of CoFe/MgO thin films. It indicates that appropriate N doping to CoFe thin film can greatly enhance the perpendicular magnetic anisotropy (PMA), while excess N doping turns the easy axis of magnetization to in-plane. Layer-resolved MAE reveals that N doping can modulate the MAE of the layers of thin film, and the projected density of states near the Fermi level becomes larger contributing to the PMA. Furthermore, the charges transfer between N atoms and Co/Fe atoms leads to charge re-distribution of Co/Fe layers, which is also helpful to improve the PMA. Our findings demonstrate the feasibility of significant enhancements in the magnetic anisotropy of CoFe/MgO thin films through the interstitial doping with nitrogen.