Magnetic Properties and Crystallographic Structure of Fe$_{3}$ Pt Thin Films

Fe
_100-x
Pt
_x
(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 (400-700degC), and heating process. Crystallographic structure obtained by X-ray diffraction (XRD) indicated that ordering of L1
₂
Fe
₃
Pt phase takes place for Fe
₇₅
Pt
₂₅
postannealed above 400degC. Ordering parameter of the Fe
₇₅
Pt
₂₅
sample increases from 0.29 to 0.94 as annealing temperature rises from 400degC to 700degC. Saturation magnetization 1270 emu/cm
³
was obtained in Fe
₇₅
Pt
₂₅
films annealed at 700degC. Fe
₇₀
Pt
₃₀
films annealed at 700degC show similar characteristics with those of Fe
₇₅
Pt
₂₅
, while Fe
₈₀
Pt
₂₀
films exhibit paramagnetism due to disordered Fe-rich face-centered cubic (fcc) structure. Postannealing seems necessary for formation of pure L1
₂
Fe
₃
Pt phase while in situ annealing leads to formation of a metastable tetragonal Fe
₃
Pt phase, as confirmed by XRD.