Growth conditions to optimize chemical order and magnetic properties in molecular-beam-epitaxy-grown CoPt/MgO(001) thin films

Abstract

CoPt films grown on MgO(001) substrates by molecular-beam epitaxy are expected to develop a very large uniaxial magnetocrystalline anisotropy and a high coercivity when the [001] single variant L10 structure develops along the growth direction. The present study investigates the growth conditions that provide the best structural quality of the films and their related magnetic properties. The quality of the substrate surface, the thickness, and the texture of the Pt buffer layer, the presence or absence of a Cr seed layer, are found to be determinants for the fraction of well-oriented grains in the films, whereas the growth temperature mainly pilots the degree of L10 order η. The uniaxial magnetocrystalline anisotropy energy of the [001] grains (Ku001) is maximum at the stoichiometric composition and shows a linear increase with η. The coercive fields and the magnetic domain size are discussed in relation to the microstructure, the degree of L10 order and the magnetic microscopic constants of the films.

Microstructural, Magnetic Anisotropy, and Magnetic Domain Structure Correlations in Epitaxial FePd Thin Films With Perpendicular Magnetic Anisotropy

“…This allows a calculation of the effective average magnetic anisotropy (K eff ) from the area enclosed between the perpendicular and in-plane M-H loops, from which K u can be obtained by correcting for the stray field contribution (K d ). 22 We observe that K u increases with the chemical ordering (S order ) of the FePd films as indicated in Table II, in agreement with previous observations for strong PMA materials. 19 The effects of these changes in chemical ordering parameter (S order ) and the first order uniaxial anisotropy constant (K u ) on the magnetic domain size/period was investigated using an analytical energy model for high anisotropy materials.…”

The perpendicular magnetic anisotropy of CoPt/Au multilayer films

“…The sample was prepared on an MgO substrate at 350 °C, which is a starting temperature of L1 0 phase formation in this system. We expected that a film with L1 0 phase, in which the growth direction was assisted by the orientation of an MgO substrate, was produced [19]. (Figure 3(a)).…”

“…For example, CoPt film should have a (0 0 1) texture. In general, different kinds of seed layers such as MgO, Ag, and Mo are effective in controlling the crystal orientation [17][18][19][20]. Furthermore, a multilayered structure also produced perpendicular anisotropy [21][22][23].…”

Saddle-point energies and Monte Carlo simulation of the long-range order relaxation in CoPt

“…Systems presenting a phase diagram derived from the Au-Cu canonical phase digram are among the most studied. Owing to their high magnetic anisotropy, some of them in the iron-group metals and platinum group metals are of outstanding technological importance [1,2,3,4,5]. A good knowledge of the ordering process and its dynamics is thus a necessary step in any extensive research on these systems.…”