An ab initio study on half-metallicity and lattice dynamics stability of ternary half-Heusler vanadium antimonides: VXSb (X = Co, Rh, and Ir)

Abstract

Ternary half-Heusler VXSb (X = Co, Rh, and Ir) antimonides having C1b cubic crystal structure and conforming to F4‾3m space group with 216 space number, have been investigated in α, β, and γ structural phases with ab initio simulation methods. First, the gamma phase was found to be the most favorable atomic arrangement from the enthalpies of formation and energy-volume curves calculated for these materials. Then, the electronic nature, some mechanical properties, and lattice dynamical stability were investigated in the most stable γ phase. While examining the electronic behavior of these compounds, both GGA + PBE and mBJ approaches have been used to observe the band gaps. As a result of the electronic band structure calculations, it is understood that these compounds have a half-metallic nature with 100% spin polarization. In addition, the total magnetic moments of these half-metallic ferromagnets are found to have an integer value of 1 μB per formula, which is consistent with the Slater-Pauling rule. These crystal systems have mechanical stability because the elastic constants satisfy the Born-Huang stability criteria. Besides, it has been observed that the materials exhibit ductile and anisotropic behavior. Finally, phonon dispersion curves and some thermodynamic properties for these systems were obtained and it was seen that they have lattice dynamics stability. The results obtained in this study show that these compounds are suitable candidates for spintronic applications at room temperature.