Investigation of structural, electronic, half metallic andmagnetic properties of some XYZ, X2YZ AND XX'YZ (X, X', Y:transition metals, Z: III-V A group elements) compounds

In this study, the structural, electronic, half metallic and magnetic calculations of CoZrGe, VZrAs, VZrSb half-Heusler; Ir2MnSi, Mn2IrAl, Mn2ReSb, Ti2ReSi full Heusler; quaternary CoMoMnSb, CoTcMnSb Heusler and compounds obtained by doping Cr to 4d transition metals of these quaternary compounds in the ratios of 0.25, 0.50 and 0.75 were performed by using Generalized Gradient Approximation (GGA) and Tran Blaha modified Becke Johnson (TB_mBJ) methods with Density Functional Theory (DFT) based WIEN2k program. The ground state values of the compounds were obtained by fitting the energy-volume optimization curves for ferromagnetic (FM) and non-magnetic (NM) phases with the Murnaghan's equation of state. According to the curves drawn, ferromagnetic phases are more stable energetically for each compound than non-magnetic phases. The equilibrium lattice parameters of cubic compounds were obtained as 5,91; 6,22; 6,50 Å for CoZrGe, VZrAs, VZrSb half-Heusler compounds; 6,03; 5,93; 6,17; 6,19 Å for Ir2MnSi, Mn2IrAl, Mn2ReSb, Ti2ReSi full Heusler compounds; 6,21; 6,19; 6,16; 6,16 Å for Crx (x = 0, 0.25, 0.50 and 0.75) doped CoMnMo1-xSb compounds, and 6,16; 6,14; 6,13 and 6,10 Å for Crx (x = 0, 0.25, 0.50 and 0.75) doped CoTc1-xMnSb compounds, respectively. While half-metallic band gaps in CoZrGe and VZrAs half-Heusler compounds were obtained in TB_mBJ method, these gaps in VZrSb compound were obtained in both methods. While Mn2ReSb compound has half-metallic band gap in TB_mBJ method, all remaining full Heusler compounds have band gaps in both methods. The band gaps of Crx (x = 0, 0.25, 0.50 and 0.75) doped quaternary Co(Mo, Tc)1-xMnSb compounds at the ratios of x = 0 and 0.25 can not be obtained in the GGA method, while the half-metallic band gaps were obtained at the ratios of x = 0.25, 0.50 and 0.75 in the TB_mBJ method. The total magnetic moment values obtained for each compound were found to be compatible with the Slater-Pauling (SP) rule.