First-Principles Calculations Study of Structural, Elastic, Electronic and Optical Properties of Co2 − xVxFeGe Full-Heusler Alloys.

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 Co_2−xV_xFeGe. Our investigation reveals that the compound Co_1.25V_0.75FeGe exhibits ideal half-metallic ferromagnetism. Additionally, the compound Co_2−xV_xFeGe 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]