First principles study of the electronic and magnetic properties of semi-Heusler alloys NiXSb (X = Ti, V, Cr and Mn)

The electronic density of states (DOS), magnetic moments and band structure of semi-Heusler alloy NiXSb (where X = Ti, V, Cr and Mn) has been studied by using the first principles full-potential linearized augmented plane wave method (FP-LAPW) based on density functional theory (DFT). For the exchange and correlation potential generalized-gradient approximation (GGA) is used. From the observations, NiTiSb shows the possibility of half-metallic ferromagnet (HMF) behavior with a band gap of 0.53 eV and an effective moment of 0.35 μB. The alloys like NiVSb, NiCrSb and NiMnSb are HMF with band gap of 0.49 eV, 0.38 eV and 0.48 eV and an effective moment of 1.995 μB, 3.01 μB and 3.99 μB respectively. DOS and band structure result shows the 3d states of Ni overlap with 3d states of X atoms suggesting hybridization between them. The exchange-splitting of Ni-3d and X-3d state electrons lead to localized spin moment which determines the HMF behavior of NiXSb. The results obtained are compared and found to be in close agreement with the available data.

► First principles FP-LAPW method is used to calculate the structural optimization, DOS, magnetic moments and band structures of NiXSb (where X = Ti, V, Cr and Mn) systems. ► Our result explains the half-metallic ferromagnetic (HMF) behavior of NiXSb in its ground state except that NiTiSb is nearly HMF. ► Exchange splitting of X-3d and Ni-3d ions were observed and explained in detail. ► Effective moment of NiXSb is found to be an integer with an energy gap at Fermi level in spin down channel. This confirms the HMF's of the compound.