Growth of L10 ordered FePt alloy films at reduced temperatures

Abstract

In this work, polycrystalline fct(001) FexPt1−x alloy thin films (with x ≈ 50 at%) have been successfully grown at reduced temperatures by dc magnetron sputtering, via two different deposition methods: a conventional cosputtering and an alternate monatomic layer (AML) deposition process. The FePt films were grown on MgO(100) substrates, with and without a Pt fcc(100) buffer layer (∼55 nm), at substrate temperatures (TS) ranging from 200 °C to 600 °C. For FePt alloy grown directly on MgO, the X-ray diffraction (XRD) analysis shows the presence of the fct(001) phase and long-range chemical order parameter (S) of 0.31, in the film prepared by AML deposition at 400 °C. For FePt alloy grown on Pt/MgO substrates, the XRD data reveal the presence of the fct(001) phase, with S ≈ 0.41, in the films deposited at TS = 300 °C by both methods. In the samples with the Pt buffer layer pre-deposited at high TS (500 °C), the presence of the fct(001) phase and high chemical order (S = 0.88) is observed for the alloy prepared by AML deposition at 400 °C. Hysteresis measurements, using Vibrating sample magnetrometry, show the presence of perpendicular magnetic anisotropy and perpendicular coercivity of 1.4 kOe for the FePt films with the definite fct(001) phase. The experimental results demonstrate the feasibility to grow FePt films with ordered fct(001) phase at moderate TS. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)