Isomorphic heteromagnetism of an Fe2MnGa alloy in a face-centered cubic structure

Abstract

The magnetic properties of isomorphic heterogeneous γ-Fe2MnGa alloys were investigated by means of experiments and calculations. Fe2MnGa alloys subject to rapid cooling and annealing treatment show the same face-centered cubic structure at room temperature, but significantly different magnetic properties: the molecular magnetic moments are 2.11 and 4.49 μB, while the Curie temperatures are 500 and 785 K. By combining the experimental and theoretical calculation results, it can be determined that disordered atomic occupation results in magnetic diversity in the same matrix structure. Rapid solidification introduces dislocated atoms, speculated to be due to partial interchange of Mn and Fe atoms with Ga atoms, which leads to an antiferromagnetic phase, while annealing can improve the degree of atomic order and transform the antiferromagnetic into a ferromagnetic phase. The change in the atomic occupation also leads to variation of the coercivity and a magnetic phase transition.