First-principles calculations to investigate Electronic, half-metallicity, thermodynamics, thermoelectric and mechanical properties of new Half-Heusler alloys FeCoZ (Z = Si, Ge, and Pb)

Abstract

FeCoZ compounds (where Z = Si, Ge, or Pb) are essential for spintronics and thermoelectric applications. This study, using density functional theory and PBE-GGA for exchange–correlation, explores their structural, electrical, magnetic, thermoelectric, thermodynamic, and elastic properties. Density of states analysis and spin-polarized band structures indicate that all three compounds have an indirect bandgap in the spin-up (↑) channel and are metallic in the spin-down (↓) channel. The exchange mechanism is finally produced by splitting the degeneracy of Co’s 3d-states via the John-Teller distortion. Ferromagnetic stability in FeCoZ (Z = Si, Ge, or Pb) is shown by negative N_oα and N_oβ values. Thermoelectric properties are derived using the BoltzTraP method. The increasing PF in alloys indicates their potential use in high-temperature thermoelectric applications. Consequently, the elevated ZT value produced in the spin-up condition indicates that these alloys are suitable for thermoelectric applications, and the quasi-harmonic Debye model indicates thermodynamic stability. Poisson’s ratio, Pugh’s ratio, and Cauchy’s pressure confirm mechanical stability and ductility. Overall, these compounds, suited for spintronic applications, exhibit half-metallicity, ferromagnetism, and high intrinsic magnetic moments.