Effect of Spin-Orbit Coupling (SOC) On the Electronic and Thermoelectric Properties of TiCoBi Half Heusler Alloy

Umukoro JO, Omagbemi OG and Osafile OE

Published on: 2022-06-28

Abstract

There is a need for more effective thermoelectric materials for various applications in the energy sector. However, to correctly predict the thermoelectric properties of a material, the relationship among the parameters of the dimensionless figure of merit needs to be well understood. In this work, we have carried out a first-principles calculation to investigate the structural, electronic, and transport properties of TiCoBi half Heusler alloy based on the density functional theory using the generalised gradient approximation implemented in the quantum espresso suite. The band gap, lattice constant and other structural and electronic property results obtained in this work without spin-orbit coupling compare well with theoretical results from previous work. The SOC calculations increase the alloy's bandgap from 0.903 eV to 0.9337 eV. There are no results for calculations with the spin-orbit coupling considered in other work to compare. We Further presented results for the transport properties of the alloy with and without SOC. SOC calculation suggests that the n-type semiconductor of TiCoBi is a better thermoelectric material compared to the p-type; this is supported by the behaviour of the power factor per relaxation time that increases from in the calculation without SOC to in calculation with SOC.