Heusler-type metamagnetic shape memory alloys (MMSMAs) exhibit a large functional response associated with a first-order martensitic transformation (MT). The strong magneto-structural coupling combined with the presence of mixed magnetic interactions enables controlling this MT by means of a magnetic field, resulting in different multifunctional properties, among them giant magnetoresistance, metamagnetic shape memory effect (MMSM), or inverse magnetocaloric effect (MCE). Not only the shift rate of MT as a function of the magnetic field but also its eventual suppression are key parameters in order to develop these effects. Here we present our findings concerning a detailed study of the magnetic field-induced MT and its suppression in MnNi(Fe)Sn MMSMAs, by applying strong steady magnetic fields up to 33 T. These measurements will lead to the creation of the T-μ₀H phase diagrams of the MT. Moreover, we will also give light to the effect of Fe—content and, as a direct consequence, the magnetic coupling on the suppression of the magnetostructural transformation.

Heusler metamagnetic shape memory alloys (MMSMAs) show a large functional response associated with a first order martensitic transformation (MT). The strong magneto-structural coupling together with mixed magnetic interactions enable controlling this MT by means of magnetic field resulting in different multifunctional properties such as giant magnetoresistance, metamagnetic shape-memory effect (MMSM), or inverse magnetocaloric effect (MCE). Both the shift rate of MT as a function of the magnetic field and its eventual suppression are key parameters for the development of all these effects. In this work we present our findings regarding the use of strong steady magnetic fields, up to 33 T, to study in detail the magnetic field induced MT and its suppression in MnNi(Fe)Sn MMSMAs, leading to creation of the T-0H phase diagrams of the MT. Moreover, we have analyzed the impact of Fe - doping and, as direct consequence, the magnetic coupling on the suppression of the magnetostructural transformation.