First-principles study of structural, elastic, thermodynamic, electronic and magnetic properties for the quaternary Heusler alloys CoRuFeZ (Z = Si, Ge, Sn)

The electronic structure and magnetic properties of CoRuFeZ (Z = Si, Ge, and Sn) quaternary Heusler compounds were investigated using the full-potential linearized augmented plane wave (FPLAPW) method in framework of the density functional theory (DFT). The results showed that CoRuFeZ (Z = Si, Ge, and Sn) compounds were stable in Y-typel structure. By use the GGA-mBJ, the CoRuFeGe and CoRuFeSn compounds were true half-metallic (HM) ferromagnets. The CoRuFeSi had a nearly HM characteristic. The minority band gaps were 0.557 eV, 0.444 eV and 0.428 eV for CoRuFeSi, CoRuFeGe and CoRuFeSn, respectively. The total magnetic moments of CoRuFeGe and CoRuFeSn compounds were obtained 5 mu(B) per formula unit, which were in agreement with Slater-Pauling rule M-tot = (Z(tot) - 24). CoFeTiSi alloy can transform from a nearly half-metallic to a half-metallic alloy by employing a little expansion stress (+1.725% relatively to the equilibrium lattice constant a(0)). The half-metalliciy characteristic exists in relatively wide ranges of 5.9-6.9 angstrom, 5.825-6.063 angstrom and 5.921-7.187 angstrom for CoRuFeSi, CoRuFeGe and CoRuFeSn compounds, respectively, which makes them promising candidates in spintronics. (C) 2016 Elsevier B.V. All rights reserved.