Lowering of ordering temperature for L1(0)-FePt in FePt/Cu multilayers

FePt/Cu multilayers and FePt thin films were prepared by DC magnetron sputtering. The as-prepared samples were annealed in vacuum at a temperature range of 300-550 degrees C for 1 h. It is found that the addition of Cu could reduce the ordering temperature of FePt. The ordering parameter S was evaluated to be 0.6, and the coercivity reached 421 kA/m in [FePt(4 nm)/Cu(0.2 nm)](10) multilayers annealed at 350 degrees C. The Cu layer induced reduction of ordering temperature is ascribed to both kinetic and thermodynamic factors.