Control of the Microstructure of FePt-SiN $_{\rm x}$ -C (001) Film by a Nucleation Layer Grown on TiN Intermediate Layer

The microstructure and magnetic properties of granular FePt-SiN_x-C films were modified by introducing an MgO nucleation layer grown on the TiN intermediate layer. It was found that the deposition of an ultra-thin MgO nucleation layer could reduce the FePt grain size, narrow grain size distribution and improve grain isolation by creating more nucleation sites. When MgO nucleation layer thickness varied from 0 to 0.36 nm, FePt grain size was reduced from 8.51 nm to 7.18 nm and the standard deviation of the grain size distribution was narrowed from 2.16 nm to 1.51 nm. Good L1₀ (001) texture was maintained and large out-of-plane coercivity (27.5 kOe) was obtained at the MgO thickness of 0.36 nm. Meanwhile, Δθ₅₀ of FePt (001) peak decreased from 7.1° to 6.4°, indicating the improved easy axis distribution of FePt grains. However, with the further increase of the MgO nucleation layer thickness, MgO nuclei developed into a continuous layer, FePt (111) orientation appeared and the perpendicular magnetic anisotropy was deteriorated.