Artificial Fabrication and Order Parameter Estimation of L10-ordered FeNi Thin Film Grown on a AuNi Buffer Layer

Epitaxial L10-ordered FeNi thin films were artificially fabricated on a nonmagnetic AuNi buffer layer by using an alternate monatomic layer deposition. A uniaxial magnetic anisotropy energy of the FeNi layer was estimated to be 5.8 × 106 erg/cm3 from magnetization measurements, which is the largest energy among values reported on FeNi thin films grown on nonmagnetic buffers. A long-range order parameter of the FeNi layer was estimated to be 0.330 from a grazing incidence X-ray diffraction (GI-XRD) using synchrotron radiation. We also investigated the relation between the ratio of c-axis lattice constant to a-axis lattice constant (c/a ratio) and the uniaxial magnetic anisotropy energy of FeNi thin films grown on several buffer layers. The uniaxial magnetic anisotropy energy monotonically increased with the increase in the c/a ratio, whereas the anisotropy had no clear relation with the long-range order parameter. Not only the improved long-range order parameter but optimized c/a ratio in FeNi are expected to lead to the enhancement of the perpendicular magnetic anisotropy.