Structure and magnetic properties of FePt and FePt/C thin films by post-annealing

FePt and FePt/C thin films were prepared by RF magnetron sputtering, then post-annealed in vacuum. The as-deposited films were in disordered state, and the ordered L10 structure was obtained by post-annealing at 550 deg. C for 30 min. Superlattice peaks (0 0 1) and (1 1 0) can be found in the X-ray diffraction pattern of FePt and FePt/C films, which indicate that the FCC phase has been partially transformed into L10 phase. As the thickness of C layer increased from 1 to 3 nm, the coercivities of the FePt/C multilayer decreased from 6.3 to 1.8 kOe, which indicated that thicker carbon layers in the sample would produce a higher activation energy barrier for the disorder-order transformation. With increasing the C concentration, the grain size and intergrain interactions of FePt/C multilayer films were decreased