Asymmetric magnetic-field-induced phase transformation in Fe48Mn24Ga28 Heusler alloy

Abstract

We report on the conceptual design and experimental realization of a ternary Heusler-based ferromagnetic martensitic phase transformation alloy Fe48Mn24Ga28 that exhibits asymmetric magnetostructural coupling between the forward austenite-to-martensite and the reverse martensite-to-austenite phase transformations. By tuning the Curie temperature of the high-temperature austenite to be within the thermal hysteresis of the first-order phase transformation, dissimilar change in magnetization can be associated with the forward and reverse phase transformations, respectively. We show that such an asymmetry leads to enlargement of the thermal hysteresis with an applied external magnetic field. Furthermore, partly due to the field-enhanced thermal hysteresis, the magnetic-field-induced martensitic phase transformation is irreversible in such a system. This work suggests the intricate correlation between magnetostructural coupling, thermal hysteresis, and magnetic-field-induced phase transformation, which can be exploited for designing magnetic phase transformation alloys that show extended functionalities.