Effect of spin-orbital coupling on the electronic, mechanical, thermoelectric, and vibrational properties of XPtBi (X = Sc and Y): A first-principles study

Abstract

Heusler compounds constitute a versatile class of materials, as evidenced by their numerous technological applications. Herein, we report a comparative study of the electronic, mechanical, vibrational, and thermoelectric properties of half-Heusler compounds XPtBi (X = Sc and Y) based on first-principles calculations, with and without spin-orbital coupling (SOC). The plane-wave pseudo-potential approach within density functional theory (DFT) and the Boltzmann transport equations have been used to compute these properties. SOC has a considerable effect on the electronic band structures of XPtBi (X = Sc and Y), leading to band inversion without breaking any symmetry. This band inversion results in the emergence of a topological phase in ScPtBi and YPtBi. Phonon dispersion curves and phonon densities of state have been calculated for these compounds, with and without SOC, for comparison. The calculations also reveal that, with the inclusion of SOC, these materials have improved thermoelectric properties, with figures of merit (ZT) of 0.41 for ScPtBi and 0.35 for YPtBi at 1200 K. Hence, these are promising thermoelectric materials for use at higher temperatures.