Computational Study of Structural, Electronic, Elastic, Half-Metallic and Thermoelectric Properties of CoCrScZ (Z=Al, Si, Ge, and Ga) Quaternary Heusler Alloys

Abstract

The structure, electronic, half-metallic, elastic, and thermoelectric properties of the innovative quaternary Heusler (QH) CoCrScZ (Z=Al, Si, Ge, and Ga) alloys are studied by using density functional theory (DFT). CoCrScZ (Z=Al, Ga, and Ge) materials are found to be magnetically active with 100% spin polarization where partially filled 3d-orbitals of Cr confirm the major contribution to the magnetic moment. The results of half-metallic robustness show that the mechanical stability and half-metallicity of CoCrScZ (Z=Ga and Al) can be well maintained in the range of 5.79 to 6.28 A and 5.84 to 6.33 A, respectively. The QH CoCrScSi has a magnetic moment of 4.0 μB at the equilibrium lattice constant a = 6.04 A. The calculated Cauchy pressure, Pugh, and Poisson ratio prove that all alloys are hard, elastically ductile, and anisotropic. In addition, the temperature-dependent thermoelectric properties have been studied by calculating the electronic thermal conductivity (κ), Seebeck coefficient (S), power factor (PF), and electrical conductivity (σ/τ). High ZT values of 0.15, 0.12, 0.77, and 0.83 were obtained for CoCrScSi, CoCrScGe, CoCrScAl, and CoCrScGa, respectively. Based on our calculations, CoCrScZ (Z=Al, Ge, and Ga) combine both good spintronic and thermoelectric behaviors that may be used in spin injection applications.