Preparation of L1₀ ordered FePd, FePt, and CoPt thin films with flat surfaces on MgO(001) single-crystal substrates

¹ Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo, 112-8551, Japan
² Graduate School of Fine Arts, Tokyo University of the Arts, 12-8 Ueno-koen, Taito-ku, Tokyo, 110-8714, Japan

Abstract

FePd, FePt, and CoPt alloy thin films are prepared on MgO(001) single-crystal substrates by employing a two-step method consisting of sputter deposition at low-temperature (room temperature) followed by high-temperature annealing at 600 °C. FePd, FePt, and CoPt single-crystal films with disordered structure (A1) grow epitaxially on MgO substrates at room temperature. By annealing these disordered films at 600 °C, a transformation from A1 to L1₀-ordered phase occurs. The order degrees of annealed FePd, FePt, and CoPt films are 0.63, 0.38, and 0.16, respectively. The films before annealing have very flat surfaces and the flat surfaces are kept after annealing. The arithmetical mean surface roughness values of annealed FePd, FePt, and CoPt films are 0.3, 0.1, and 0.2 nm, respectively. The two-step method is considered to be useful for preparation of FePd, FePt, and CoPt alloy thin films with flat surfaces, which are necessary for practical applications.