Investigation of electronic structure, magnetic properties and thermal properties of the new half-metallic ferromagnetic full-Heusler alloys Cr₂GdSi_1−xGe_x: An ab-initio study

We have studied the structural, electronic, elastic, magnetic, thermal and thermodynamic properties of the quaternary Heusler alloys Cr₂GdSi_1−xGe_x (x = 0, 0.25, 0.5, 0.75, 1) with the linearized augmented plane wave method based on density functional theory and implemented in WIEN2K code. For exchange correlation potential, we have used the generalized gradient approximation (GGA) within the Perdew-Burke-Ernzerhof (PBE 96) parameterization. Our results provide a theoretical study for the mixed Heusler Cr₂GdSi_1−xGe_x (0 < x < 1) in which no experimental or theoretical data are currently available. In their equilibrium L2₁ structure, all concentrations are magnetic and metallic. However, there is linear variation of the lattice parameter. The bulk modulus, the elastic constants and the Debye temperature was studied with variation of composition x of Ge. A regular solution model is used to investigate the thermodynamic stability, which are essentially shows a miscibility gap phase by calculating the critical temperatures for our alloys. In addition, the quasi-harmonic Debye model is applied to determine the thermal properties. - Highlights: • Based on DFT, GGA calculations, Cr₂GdSi_1−xGe_x compound have been investigated. • Single and polycrystalline elastic parameters are predicted. • The electronic and magnetic structure reveals the HMF character of these compounds. • The thermodynamic and thermal properties are predicted.