Magnetic Properties and Crystallographic Structure of Fe3Pt Thin Films

Fe100-xPtx (x = 20, 25, and 30) thin films with nominal thickness 50 nm were prepared by radio-frequency (RF) magnetron sputtering onto glass substrates. Crystallographic structure and magnetic properties of such films were investigated by varying Fe content, annealing temperature (400-700 degrees C), and heating process. Crystallographic structure obtained by X-ray diffraction (XRD) indicated that ordering of L1(2) Fe3Pt phase takes place for Fe75Pt25 postannealed above 400 degrees C. Ordering parameter of the Fe75Pt25 Sample increases from 0.29 to 0.94 as annealing temperature rises from 400 degrees C to 700 degrees C. Saturation magnetization 1270 emu/cm(3) was obtained in Fe75Pt25 films annealed at 700 degrees C. Fe70Pt30 films annealed at 700 degrees C show similar characteristics with those of Fe75Pt25, while Fe80Pt20 films exhibit paramagnetism due to disordered Fe-rich face-centered cubic (fcc) structure. Postannealing seems necessary for formation of pure L1(2) Fe3Pt phase while in situ annealing leads to formation of a metastable tetragonal Fe3Pt phase, as confirmed by XRD.