First-principles calculations on ferromagnetic quaternary half metal FeZrTiGe for spintronic and thermoelectric...

In the present work, we systematically investigate the structural, magnetic, electronic, elastic, thermodynamic, and thermoelectric properties of the quaternary Heusler alloy FeZrTiGe using the full-potential linearized augmented plane wave (FP-LAPW) method as implemented in WIEN2k. The calculations are performed within both the generalized gradient approximation (GGA) and GGA + U frameworks to accurately imprisonment the effects of electronic correlations on the material properties. The compound crystallizes in the α-type structure with space group F-4̅3m (#216) and exhibits a stable ferromagnetic ground state with a total magnetic moment of 2 µB. The electronic structure confirms a robust half-metallic character, exhibiting metallic behavior in the spin-up channel and semiconducting behavior in the spin-down channel, resulting in 100% spin polarization at the Fermi level and indicating its strong potential for spintronic applications. Thermodynamic analysis using the quasi-harmonic Debye model indicates stable behavior over a wide temperature and pressure range. Additionally, the negative formation energy and positive cohesive energy, together with the absence of imaginary phonon modes, confirm the thermodynamic and dynamical stability of FeZrTiGe. Elastic constants verify mechanical stability, ductility, and anisotropy. Thermoelectric calculations reveal an increasing Seebeck coefficient with temperature, reaching ~ 88.10 µV/K (GGA) and ~ 112.72 µV/K (GGA + U) at 1000 K, with ZT values of ~ 0.40 and ~ 0.50, respectively. The inclusion of on-site Coulomb interaction enhances both electronic and thermoelectric properties, establishing it as a promising candidate for spintronic and high-temperature thermoelectric applications.