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The structural, magnetic and electronic properties of two samples with nominal compositions Ni50Fe20Ga30 (NFG-1) and Ni45Fe25Ga30 (NFG-2) have been studied. With increasing Fe substitution in place of Ni atoms, the valence electron concentration per unit cell (e/a) ratio decreased from 7.59 to 7.42. This decrease in e/a ratio results in increase Tc and saturation magnetization in NFG-2 compared to NFG-1. Photoelectron spectroscopy (PES) measurements have been carried out at 20 K and 300 K for both the samples. A comparison of the calculated (first principles) and the measured density of states (by PES) show that NFG-1 undergoes a martensite phase transition, whereas no such transition is observed for NFG-2.

In this work we have predicted the mechanical and magnetic properties of cubic austenite phase of the Cu substituted alloys of Ni2MnGa and Mn2NiGa at the Ga site i.e. Ni2MnCu and Mn2NiCu, respectively, as well as of Pt2MnCu and Pd2MnCu. We have observed that the conventional Heusler structure is lower in energy compared to the inverse Heusler structure for the Ni2MnGa, Pt2MnGa and Pd2MnGa and the Cu-substituted materials, whereas Mn2NiGa and its Cu-substituted alloy at Ga site assume the inverse structure. From the calculated elastic constants, we find that Pt2MnCu is expected to be the most ductile material among all the substituted materials studied here. We have calculated and compared the Curie temperatures derived from the Heisenberg exchange coupling parameters.