The effect of a Bi underlayer on FePt thin film

Abstract

In this paper, the FePt films with Bi underlayer were prepared by dc magnetron sputtering on glass substrates. The L10-FePt films were obtained after the deposited samples were subjected to vacuum annealing at various temperatures. The effect of a Bi underlayer on the ordering temperature and magnetic properties of FePt films was studied. Experimental results show that the FePt film can realize the low-temperature ordering at 350℃ after introduction of a Bi underlayer. Moreover, the Bi underlayer can also obviously enhance the coercivity Hc of the film and enlarge the concentration range of FePt films with high Hc. We studied the distribution of Bi atoms by X-ray photoelectron spectroscopy and the change of crystal structure of FePt films by X-ray diffraction. The cause of the above observatious is associated with enhanced ordering degree of FePt films by the Bi diffusion during annealing process.