Stabilities and half-metallic ferromagnets features of new quaternary Heusler alloys RhCoVX (X = Si, Ge and Sn). Ab-initio study

Abstract

New quaternary Heusler alloys (QHAs) RhCoVX (X = Si, Ge, and Sn) were investigated for stability and half-metallic ferromagnet features. Three nonequivalent structural arrangements of type I, II, and III structures are considered. Type I is described as the most stable phase for all these compounds in ferromagnetic order compared to non-magnetic order. We also demonstrate the thermodynamic, dynamic, and mechanical stability of RhCoVX (X = Si, Ge, and Sn) by computing the cohesive energies, formation energies, phonon dispersion curves, and elastic constants. Using GGA-mBJ and LDA-mBJ calculations show that RhCoVX (X = Si, Ge, and Sn) are half-metallic ferromagnets (HMFs), with indirect bandgap through the altered Becke-Johnson (mBJ), in the two approach's LDA-mBJ and GGA-mBJ: 1.03 eV (0.922 eV) for RhCoVSi, 0.956 eV (0.856 eV) for RhCoVGe and 0.706 eV (0.662 eV) for RhCoVSn. Furthermore, the electrons at the Fermi level (EF) were fully spin-polarized. The total magnetic moment in these three compounds was found as an integer value of 3.00 μB per formula, which complies with the Slater-Pauling rule Mt = Zt - 24. According to the given results, these compounds are promising materials for spintronic applications. All calculations used the density functional theory (DFT) based on the full-potential linearized augmented plane wave (FP-LAPW) method implemented in the WIEN2K code.