The structure and magnetic properties of Fe-Cr-N films, prepared by sputtering, have been investigated by X-ray diffraction, transmission electron microscopy, vibrating sample magnetometry and Mössbauer spectroscopy. We obtained a saturation magnetization of 377 emu/cm3 and a perpendicular coercivity of 6.53 × 104 A/m for a Fe71Cr20N9 film, when the N2-to-Ar flow ratio was 0.3 and the substrate temperature was 523 K. The increase of the perpendicular magnetic anisotropy is accompanied by a reduction in the grain size of the α-Fe(Cr) phase and growth of the γ′-(Fe,Cr)4Nx phase. The γ′-phase is nonmagnetic at room temperature, displaying columnar growth, and the small ferromagnetic α-Fe(Cr) grains are distributed at the grain boundaries of the γ′-(Fe,Cr)4Nx columns. The shape anisotropy plays an important role in the perpendicular magnetic anisotropy in the present films.
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