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

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 Fe ₂MnGa during the BCC-FCC transformation. Our findings unveil that the Fe ₂ MnGa 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.