Structural stability, mechanical, electronic and magnetic behaviour of quaternary ScNiCrX (X = Al, Ga) Heusler alloys under pressure

Abstract

Abstract This paper reports results on the structural stability, mechanical, electronic and magnetic behaviour of quaternary ScNiCrX (X = Al, Ga) Heusler alloys under pressure. First principles approach is applied to calculate the structural, mechanical, electronic and magnetic properties of ScNiCrX alloys under pressure. In ferromagnetic phase, both alloys (in Type-γ configuration) are stable. Over a wide pressure range, the calculations of cubic elastic constants (Cij) for both alloys fulfill the necessary criteria for structural stability. Under pressure up to 6.0 GPa, the ScNiCrAl alloy shows half-metallic ferromagnetic behaviour. The ScNiCrGa alloy exhibits half-metallic behaviour over a wide range of pressure (up to 16.0 GPa) as compared to ScNiCrAl alloy. For ScNiCrAl alloy, the spin ↓ energy band gap (Eg) increases (0.27–0.43 eV) with increase in pressure (0.0–6.0 GPa) while for ScNiCrGa alloy Eg increases from 0.30 to 0.58 eV with increase in pressure from 0.0 to 16.0 GPa. For pressure up to 10.0 GPa, the calculated total magnetic moment, MT (for both alloys) exhibit Slater-Pauling rule, MT = (NV – 18) μB. Up to 6.0 GPa, it is expected for ScNiCrAl alloy to show 100% spin-polarization (at Fermi-level, EF) while for ScNiCrGa alloy, 100% spin-polarization is possible to achieve for pressure up to 16.0 GPa. On the basis of results, it is suggested that the ScNiCrX Heusler alloys could be suitable candidates for spintronic devices to operate under harsh environment.