Low-temperature in-situ growth of high-coercivity Fe-Pt films

FePt films with high coercivity, large energy product and corrosion resistance, have high potential in applications such as MEMs and ultra-high density magnetic recording. Much attention has been paid to the preparation of high quality films at substrate/annealing temperatures as low as possible to accommodate processing adopted in the manufacture of MEMs or sensors. In this study Fe_xPt_1-x thin films were deposited by DC magnetron sputtering onto Si(100) and CrMo-seeded glass substrates at a substrate temperature (Ts) 30 to 600°C with or without further post-annealing. Optimum magnetic properties of our studied films were obtained at the Fe₅₃Pt ₄₇ composition as-deposited at Ts 300°C. The in-plane coercivity (Hc) is 8 kOe for as-deposited films on both Si(100) and glass substrates. The films on Si(100) showed a maximum magnetization (M2T) and a maximum energy product of 950 emu/cm³ and 15.8 MGOe, respectively. The squareness ratio (M_r/M_s) of the as-deposited FePt films on glass substrate increases with increasing Ts. Minor hysteresis loops reveal that domain-wall-pinning dominates the magnetic hardening of the FePt films. Post annealing at 400°C substantially enhances coercivity and energy product for the Fe₅₃Pt₄₇ films on glass substrate. Ordering parameters were studied by XRD and quantitatively correlated to magnetic properties