Study of structural, magnetic and electronic properties of Ni-Fe-Ga based ferromagnetic shape memory alloys

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.