Annealing temperature dependent structures and properties of ferromagnetic Fe₃Si films fabricated by resistive thermal evaporation

Fe₃Si films were fabricated on quartz substrates using resistive thermal evaporation technique and the influence of annealing temperature on structures and properties of these films were investigated. XRD results show that the single phase Fe₃Si films have been obtained at annealing temperature ranging from 850 to 950 °C. The structure of Fe₃Si films transforms from body centered cubic to face centered cubic structure with the increase of annealing temperature. SEM images reveal that the particle sizes of these polycrystalline films are about 1–3 μm in dimension with island-like feature, and then a drastic change in the appearance with flake-like feature occurs at 950 °C. The electrical resistivity first increases with increasing annealing temperature reaching a maximum at 900 °C and then rapidly decreases. It implies the further diffusion between Fe and Si atoms and atomic rearrangements toward a more ordered structure. The magnetization curves exhibit that all the films are ferromagnetic at room temperature. This in-plane magnetic anisotropy plus the sharp anisotropy make easy magnetization of these films parallel to the film surface. The face centered cubic structure Fe₃Si film at 950 °C shows a high M _s value of ~972 emu/cm³ and a small H _c value of ~9 Oe, close to the bulk value.