Prodigious half Heusler alloys VIrX (X = As and Sb) for waste heat recovery systems and spintronics applications – unravelled by DFT

In this paper, we investigate the electronic, magnetic, mechanical, and thermoelectric properties of half Heusler compounds VIrAs and VIrSb by first principles calculations. The crystal structure of the half Heuslers was optimized and the lattice parameters of VIrX (X = As and Sb) were found to be 5.8754 and 6.1152 angstrom, respectively. The calculated elastic constants reveal the mechanical stability of the materials. Additionally, the phonon dispersion studies prove their dynamical stability. The GGA and TB-mBJ exchange correlational functionals were used to calculate the electronic properties. The density of states shows 100% spin polarization at the Fermi level. The half-metallic property is confirmed by the band gap observed in the spin-down channel, showing the semiconductor property and the metallic character in the spin-up channel. The half Heuslers were found to be ferromagnetic in the stable configuration. The major contribution to the ferromagnetic property was due to V atoms. Furthermore, the thermoelectric properties were also studied, and remarkable values of the figure of merit of 1.49 and 0.38 were obtained for VIrAs at 800 K and VIrSb at 600 K, respectively. Our findings reveal promising materials for thermoelectric and spintronic devices.