Control of growth and ordering process in FePt(001) film at 300 ° C

Abstract

FePt(20 nm)/Cr(200 nm) bilayer films were deposited on 300°C-heated glass substrate in order to study the sputtering rate effect on ordering process and growth mechanism of FePt films. The sputtering rate of FePt layer (Rm) was adjusted within the range from 0.1 to 2.0 nm/min.. X-ray results show a high order parameter of ~0.8 in the sample with Rm = 0.1 nm/min and a disordered phase of FePt in the film with Rm = 2.0 nm/min. As Rm = 0.1 nm/min., the orientation of FePt lattice aligns along the Cr(002) to develop (001)-oriented FePt. However, an isotropic orientation is observed in FePt layer as Rm = 2.0 nm/min.. In the case of low deposition rate, the growth of the film is dominated by surface diffusion. In contrast, the process of bulk diffusion dominates in the rapidly-deposited film. The activating barrier of bulk diffusion is about an order of magnitude larger than that of surface diffusion leading to the appearance of disorder structure and isotropic orientations at high sputtering rate. In this study, FePt layers with well-developed (001) texture and high chemical ordering can be fabricated via surface diffusion mechanism at 300°C. Our result merits the use of FePt magnetic layer for magnetic recording media in the future.