High coercive L10 FePt–C (001) nanocomopsite films with small grain size for perpendicular recording media

FePt–C films with various C concentrations were deposited on MgO∕CrRu/glass substrate by cosputtering FePt and C at 350°C. The evolution of magnetic properties and microstructure of FePt–C films with the C concentration were investigated. All FePt films showed (001) preferred orientation regardless of C concentrations. With C doping, a two-layer structure of FePt–C films was formed. The FePt–C underlying layer epitaxially grown on MgO intermediate layer were L10 FePt grains, while the FePt overlayer consisted of fcc FePt phase and L10 FePt phase. The out-of-plane coercivity measured at room temperature increased from 10.2to19kOe when C concentrations increased from 0% to 15%. Further increasing the C contents to 20% and 25% caused the decrease of coercivity to 17.2 and 14.8kOe, respectively.