Study of FePt films prepared by reactive sputtering

In the present study, 57FePt films are prepared with reactive ion beam sputtering using mixture of argon and nitrogen gases. Energy-dispersive X-ray reflectivity is used to estimate the thickness of the as-deposited films. Structural and magnetic properties of the as-deposited and annealed films are studied using grazing incidence X-ray diffraction (GIXRD), magneto-optical Kerr effect (MOKE) and conversion electron Mossbauer spectroscopy (CEMS). Significant difference in structural and magnetic properties i.e., formation of ordered L10 phase and perpendicular magnetic anisotropy are observed for the films prepared with mixture of nitrogen and argon as compared to the film prepared with argon only. From the GIXRD, peaks corresponding to the ordered face-centred tetragonal FePt phase are observed for the films prepared with mixture gas. The results of CEMS clearly show the perpendicular magnetic anisotropy (PMA) for the films prepared with mixture of nitrogen and argon. The observed enhanced chemical ordering and the development of PMA in the films prepared with mixture gas is due to the role played by the defects created as a consequence of nitrogen escape in the films with high temperature annealing.