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

We have studied L1₀-FePt thin films with a Bi underlayer. Experimental results show that the ordering temperature of the L1₀-FePt film can be lowered down to 300–350 °C and the in-plane coercivity H_C of the film is obviously enhanced by introduction of a Bi underlayer. After annealing at 400 °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 L1₀-FePt films can be understood by considering the large diffusivities of Fe and Pt associated with Bi diffusion. [ABSTRACT FROM AUTHOR]