BCC-FCC transformation induced exchange bias effect in the Fe2MnGa alloys

Abstract

Transformation from a body-centered cubic (BCC) to a face-centered cubic (FCC) phase has garnered substantial attention in materials design due to its capacity for adjustable properties. In this study, we investigated the magnetic behavior of stoichiometric Fe2MnGa during the BCC-FCC transformation. Our findings unveil that the Fe2MnGa alloy undergoes a gradual transformation from BCC to FCC phase. During this transformation, the proportion of FCC phase gradually increases, resulting in a dual-phase structure, until it ultimately reaches a pure FCC phase. Furthermore, as the cooling processes, a magnetic transition from ferromagnetic to weak magnetic state was observed within the FCC phase. Following this magnetic transition, the sample exhibits an exchange bias effect, indicating a mixed ferromagnetic/antiferromagnetic state rather than a pure antiferromagnetic state. The magnitude of the exchange bias field is directly proportional to the proportion of the FCC phase, suggesting a negligible contribution of the BCC phase to the exchange bias effect. The controllable dual-phase nature of Fe-Mn-Ga alloys holds significant potential for material design.