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Using the first-principles full-potential linearized augmented-plane-wave method with the GGA-PBE approximations, we have explored the structural, elastic, electronic, and optical characteristics of Co2−xVxFeGe. Our investigation reveals that the compound Co1.25V0.75FeGe exhibits ideal half-metallic ferromagnetism. Additionally, the compound Co2−xVxFeGe exhibits different crystal structures depending on the value of x. At x = 0.25, it has a cubic structure with a space group of P-43 m. However, at x values of 0.50 and 0.75, it undergoes a transition to a tetragonal structure with respective space groups of P42/mcm N◦ (132) and P-42 m (111). In these tetragonal structures, the compound displays anisotropic mechanical stability. Moreover, as the concentration of V increases, the volume gradually increases. These properties are crucial in determining the material's suitability for use in optoelectronic devices. The electronic properties of most of the compounds displayed half-metallicity and 100% spin polarization, particularly for the composition x = 0.75. [ABSTRACT FROM AUTHOR]

Density functional theory has been used to study the structural, elastic, electronic, magnetic and optical properties of Ti2FeSb Heusler alloy using generalised gradient approximation implemented through the WIEN2k code. The cubic structure of Ti2FeSb is mechanically stable in the F-43m space group and shows elastic anisotropic properties with ductile nature. Ti2FeSb shows spin gapless semiconductor behaviour along with an indirect energy band gap (EG) of 0.10 eV along the Г-Χ in majority spin (γ-spin) band above the Fermi energy level (EF) and 0.90 eV in the minority spin (δ-spin) band at EF. The total magnetic moment is 3 µB at optimized lattice constant (ao) 6.32 Å and follows the Slater–Pauling curve for inverse Heusler alloys. Robustness of this material with respect to change in the value of ao is evident in the constancy of magnetic moment along with retention of the half metallic nature within a lattice variation ±4% from equilibrium value of ao. Reflectivity, optical conductivity, dielectric function, absorption coefficient and energy loss have also been investigated as a function of incident energy for this alloy. [ABSTRACT FROM AUTHOR]

The first principles calculations are carried out to understand the half metallic and ferromagnetic properties of Fe2−xCoxTiSi (x = 0, 0.5, 1, 1.5, 2) full Heusler alloys. The stable structure is predicted as L21 structure (Cu2MnAl phase). The lattice constant value of Fe2−xCoxTiSi Heusler compounds increases as the value of x increases. These alloys exhibit half metallic ferromagnetism (except Fe2TiSi) with small spin flip gap at the minority spin state. At high pressure, semiconductor to metallic phase transition is observed in Fe2TiSi while half metallic to metallic phase transition is observed in Fe1.5Co0.5TiSi, Fe1.0 Co1.0TiSi, Fe0.5Co1.5TiSi and Co2TiSi. The spin polarization of these compounds (except Fe2TiSi) is 100%. Hence, these compounds are suitable for spin injection devices in spintronics. [ABSTRACT FROM AUTHOR]