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

Electronic distribution and John Teller distortion for 3d-states of Co in FeCoZ (Z =Si, Ge, and Pb) [Display omitted] •The materials are stable in their cubic structure.•The elastic properties suggest mechanical stability and ductile nature.•Each materials exhibit indirect band gap in spin up, and metal in spin dn channel.•Crystal field energies predict the stability of ferromagnetic nature.•The thermoelectric properties give valuable insight in to thermoelectric efficiency.•The thermodynamic properties clarified the thermodynamic stability. 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 Noα and Noβ 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.