Low-temperature ordering and enhanced coercivity of L10-FePt thin film promoted by a Bi underlayer

We have studied L1(0)-FePt thin films with a Bi underlayer. Experimental results show that the ordering temperature of the L1(0)-FePt film can be lowered down to 300-350 degrees C and the in-plane coercivity H-C of the film is obviously enhanced by introduction of a Bi underlayer. After annealing at 400 degrees C for 20 min, a Bi/FePt film realizes a H-C of 13.5 kOe and the ratio of the remnant magnetization M-r to. the saturation one M-S of as high as 0.93. The reduction of the ordering temperature and the enhanced magnetic properties of L1(0)-FePt films can be understood by considering the large diffusivities of Fe and Pt associated with Bi diffusion. (c) 2006 American, Institute of Physics.