FePd, FePt, and CoPt alloy epitaxial thin films with flat surface grown on MgO(111) substrate

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

^a Corresponding author: futamoto@elect.chuo-u.ac.jp

Published online: 3 July 2014

Abstract

FePd, FePt, and CoPt alloy epitaxial films of 40 nm thickness are prepared on MgO(111) singlecrystal substrates by employing two different methods. One is a one-step method consisting of hightemperature deposition at 600 °C and the other is a two-step method consisting of low-temperature deposition at 200 °C followed by annealing at 600 °C. Although the preparation method is different, similar final crystal structures are realized for all the film materials. FePd and FePt alloy films grow on the substrates with six L1₀(111) variants, whose c-axes are about 35° canted from the substrate surface and rotated around the film normal by 60° each other. The order degrees of FePd and FePt films prepared by one- and two-step methods, (S_one-step, S_two-step), are estimated to be (0.25, 0.33) and (0.08, 0.15), respectively. On the contrary, L1₀ ordered phase formation is not recognized for CoPt alloy films. The films prepared by one-step method have rough surfaces surrounded by side facets, whereas the films prepared by two-step method have very flat surfaces with the arithmetical mean roughness of 0.3 nm. The two-step method is useful for preparation of L1₀ ordered films with flat surface.