Pt diffusion driven L10 ordering in off-stoichiometric FePt thin films.

Pt/Fe3Pt thin films were deposited on the 〈100〉 silicon substrates at room temperature using DC sputtering. As-deposited Pt (25nm)/Fe3Pt (70nm) bilayers were subjected to heat treatment and a systematic study was carried out to investigate the structural and magnetic phase transition as a function of annealing temperature. The as-obtained films show an A1 disordered, face centered cubic phase which exhibit a magnetically soft behavior. After annealing at 300°C for 1h, the set in of L10 face centered tetragonal phase was observed and is attributed to the atomic diffusion at Pt/Fe3Pt interface. A coercivity of 6.8kOe was obtained for Pt/Fe3Pt at 300°C which increases to 12.5kOe at 400°C due to enhanced fct phase formation. Rutherford back scattering study has also been performed to investigate the inter-layer diffusion of Fe3Pt and Pt, along with estimation of film thickness and atomic composition with annealing temperature. The thickness and composition of films annealed at 600°C was found to be 73nm and Fe54Pt46, respectively. Lower temperature ordering is achieved for these bilayer films. [ABSTRACT FROM AUTHOR]