Structural and magnetic properties, and electronic structures of Fe-Mn-Ga alloys

We report the structural and the magnetic investigations on bulk Fe-Mn-Ga alloy and the films with a stoichiometry of 1:1:1. Both the alloy and the films reveal an unstable crystallographic structure. While the bulk alloy appears to possess a mixed ferromagnetic hexagonal structure with the presence of a (Mn/Fe) 9 Ga 5 ξ-phase, the films have ferromagnetic cubic phases in various types of structural ordering that depend on the deposition and the annealing conditions. Exchange bias and enhanced coercivity occur simultaneously in B2-type ordered FeMnGa films, revealing an exchange coupling between coexisting antiferromagnetic and ferromagnetic phases. The experimental results are compared with the results of the first-principle calculations.