Effects of composition and chemical disorder on the magnetocrystalline anisotropy of Fe_xPt_(1-x) alloys

摘要

We perform first-principles calculations of the magnetocrystalline anisotropy energy (MAE) of the L1_0-like Fe_xPt _(1-x) samples studied experimentally by Barmak and co-workers (see J. Appl. Phys., 98 (2005) 033904). The variation of composition and long-range chemical order in the samples was studied in terms of the coherent potential approximation. In accordance with experimental observations, we find that, in the presence of long-range chemical disorder, Fe-rich samples exhibit a larger MAE than stoichiometric FePt. By considering the site-and species-resolved contributions to the MAE, we infer that the MAE is primarily a function of the degree of completeness of the nominal Fe layers in the L1_0 FePt structure.