Highly Ordered FePt $L1_{0}$ Thin Films With Small Grains on RuAl Seed Layers

We present an experimental approach for obtaining highly ordered L1₀ FePt-oxide thin film media with small grains by using a RuAl layer as a grain size defining underlayer. In most previous studies, the FePt grain size was controlled by tuning the oxide volume fraction of the film. By introducing the RuAl grain size defining layer, 6 nm of FePt grains can be obtained at 520°C with 9% SiO₂ in the film. A 5 nm thin barrier layer was introduced between FePt and RuAl to prevent the inter-diffusion between RuAl and FePt. The influence of different barrier layers was studied. With a thin Ag sacrificial layer inserted between the barrier layer and the FePt magnetic layer, a smaller grain size can be achieved, the ordering temperature was lowered, and the (001) texture of FePt was enhanced.