Magnetic anisotropy and microstructure in sputtered CoPt(110) films

Orientation and magnetic properties of FePt and CoPt films grown on MgO(110) single-crystal substrate by electron-beam coevaporation

“…Such behavior is observed for the highly textured (h h 0) oriented FePt films of Ref. [3]. Because of the fourfold rotational symmetry of the L1 0 structure about the ordering direction, similar behavior is also expected along the [1 1 0] axis of the ordered L1 0 phase, which is normal to the MgO substrate for (h h 0) oriented film but not for the (h 0 h) or (0 h h) orientations.…”

“…The [11 0] substrate direction is magnetically hardest for all three deposition temperatures, with incomplete saturation of the magnetization M along this direction even for the largest applied field. The difference between the fields required to achieve saturation magnetization (M s ) in the two orthogonal directions, the (in-plane) anisotropy field, is estimated to be 6.5 T. The kinks on the loops (near applied field H = 0) are consistent with incomplete magnetic coupling between the different orientations of the tetragonal L1 0 phase in the film [3]. The appreciable field required to reach magnetization M = 0 (coer- civity) and appreciable magnetization measured at zero field (remanence) along the hard axis [11 0] direction are attributed to the incomplete (h h 0) growth and/or presence of (0 h h) and (h 0 h) orientations of the ordered L1 0 phase; low coercivity and remanence are expected along the [11 0] hard axis of the ordered L1 0 phase [2], which lies along the [11 0] substrate direction for (h h 0) oriented film but not for (h 0 h) or (0 h h) orientations.…”

“…Epitaxial cube-on-cube growth of sputtered CoPt was also achieved by Abes et al on a MgO(1 1 0) substrate at 627 • C, but the dominant (0 h h) and (h 0 h) orientations, rather than the desired (h h 0) orientation, placed an easy magnetization axis along the [11 0] substrate direction [3]. In this paper the use of electron-beam evaporation to grow epitaxial FePt and CoPt L1 0 films on MgO(1 1 0) single-crystal substrates is described.…”

“…In order to obtain the L1 0 phase ordered along a single direction, growth and/or annealing must occur in the presence of an external field that breaks the symmetry, e.g. an external magnetic field or mechanical constraint [3].…”

Monte Carlo simulations of the L10long-range order relaxation in dimensionally reduced systems

“…The discovery of the interesting properties of these materials dates back to the 1930's. They have been, however, the topic of many intensive experimental and theoretical works in the last decades (see [4,5] and references therein). A good knowledge of the ordering processes and of its dynamics is a necessary step in any extensive research on those systems.…”