Ab initio study of magnetic properties of Fe-Mn-Al Heusler alloys

摘要

Density functional theory (DFT) based on the spin-polarized relativistic Korringa-Kohn-Rostoker (SPR-KKR) method is used to investigate the magnetic properties of non-stoichiometric Fe_(2+x)Mn_(1-x)Al Heusler alloys, where 0 ≤ x ≤ 0.9. The composition dependences of the magnetic exchange couplings and the Curie temperature for the cubic L2_1 phase are obtained. Our simulations have shown that the Fe-Fe nearest neighbors present a strong ferromagnetic coupling. Moreover, these exchange interactions are larger than other interactions. The substitution of Mn by Fe in Fe_(2+x)Mn_(1-x)Al (0 ≤ x ≤ 0.9) leads to an increase in the Curie temperature. This tendency and the values of Curie temperatures are in agreement with the experimental results for Fe_(2+x)Mn_(1-x)Al (x = 0, and 0.1). The highest Curie temperature was observed for the Fe-richer alloy.