Evolution of a weak magnetic moment in the FeNbSb based HH materials via Ni doping at Fe site

Heusler based materials have been identified as a potential candidate for their wide range of applications. Most of the Heusler based material’s properties can be scaled by their valence electron count (VEC). Herein, we have synthesized Ni-doped FeNbSb half-Heusler materials by solid-state reaction route to study its magnetic properties. The XRD and microscopic study show the half- Heusler (HH) single phase for Fe _1-xNi _xNbSb (x = 0.025 and 0.05) compositions. Experimental results well corroborated the theoretically estimated magnetic moment by the Slater-Pauling rule. The XRD simulation shows atomic disorder due to swapping of nearly 50% Fe at the Nb site, which reduces the magnetic moment value accordingly. The controlled Ni-doping in the FeNbSb matrix revealed a weak magnetic moment that was not seemed to be saturated even at a high magnetic field. That directly supports the compositions to be hard magnetic materials. Moreover, for both sample’s, magnetization vs. temperature graph shows a competitive behavior between the Ferro-antiferro phase in the 5 K to 300 K temperature range associated with swapping of Fe at Nb site as well as Ni substitution.