Tailoring spin-polarized properties of HfFeX (X = Sn, Ge) half-Heusler alloys for spintronic and optoelectronic applications via DFT

Abstract

In this study, we use first-principles simulations to investigate the electrical, magnetic, mechanical, and thermoelectric properties of the half-Heusler alloys HfFeSn and HfFeGe. The equilibrium lattice constants for HfFeX (X = Sn, Ge) were found to be 6.2148 and 5.9505 Å, respectively, after structural optimization of these compounds. Both materials’ dynamical stability is confirmed by phonon dispersion analysis, and their mechanical stability is indicated by the obtained elastic constants. We used both the GGA and TB-mBJ exchange–correlation functionals to study the electronic structure. At the Fermi level, the density of states exhibits full spin polarization. Additionally, the presence of a finite band gap in the spin-down channel, which indicates semiconducting nature, and metallic behavior in the spin-up channel, confirms the half-metallic behavior. In their most stable configuration, the half-Heusler compounds display ferromagnetic ordering, with the vanadium atoms primarily responsible for this magnetism. Furthermore, an evaluation of the thermoelectric performance produced remarkable figure of merit values of 0.45 for HfFeSn and 0.50 for HfFeGe at 1000 K. These findings imply that the materials under investigation have a great deal of promise for use in spintronic and thermoelectric technologies.