Spin-orbit coupling locked robust thermoelectric performance of SrTe: A comparison with CaTe

Abstract

We have investigated the pressure dependence of structural, electronic and transport properties of cubic CaTe and SrTe using density functional theory. By employing semi-classical Boltzmann-transport-formalism their transport properties are computed within constant scattering time approximation. Without spin–orbit-coupling (SOC), one finds multiple Dirac points along various directions around the M point in the Brillouin zone. SOC opens up gaps at all points except one Dirac point along the M-R direction. We have also explored the effect of isotropic compressive strain on thermoelectric properties. The effect of SOC is prominent for SrTe results into enhanced electrical conductivity by 20 times and power factor by almost 25 times. Doping of charge carriers results in improvedZT of CaTe. However, in SrTe only electron type doping is beneficial for improving ZT. We find thatSrTe is robust 3D Dirac material with promising thermoelectric performance. Specifically, SOC results in robust thermoelectric properties against strain and temperature changes.