First-principles study of structural, elastic, mechanical, electronic, magnetic, optical, and thermoelectric properties of CoFeTe half-heusler alloy

•CoFeTe is most stable in the β-phase with a ferromagnetic configuration.•GGA-PBE shows metallic properties, while GGA + U reveals semi-metallic behavior.•Phonon and elastic analyses confirm the alloy’s mechanical stability.•The alloy’s ZT value reaches 0.2 at 800 K, showing potential for thermoelectric use.•CoFeTe holds promise for spintronic and optoelectronic applications. Half-Heusler CoFeTe alloy is analyzed using Density Functional Theory (DFT) calculations based on the GGA-PBE and GGA + U approximations. The results reveal that CoFeTe was most stable in the β-phase with a ferromagnetic configuration. As determined by the density of states analysis, metallic behavior is observed for the GGA-PBE approximation, whereas a semi metallic nature is observed for the GGA + U approximation. Phonon dispersion, elastic, and mechanical analyses confirm the dynamical and mechanical stability of the alloy. The thermoelectric properties suggest that CoFeTe shows potential for thermoelectric applications, with an increasing Seebeck coefficient and power factor, reaching a ZT value of 0.2 at 800 K. These findings highlight the potential of CoFeTe for applications in thermoelectric devices.