Thermodynamic phase diagram stability, electronic and thermoelectric properties of the half-Heusler KMgP [111] films

Abstract

The mechanical, electronic and thermoelectric calculations of the KMgP half-Heusler compound and its [111] thin films have been done in the framework of density functional theory. The KMgP bulk has mechanical stability in the static and dynamic viewpoints, and it has the p-type semiconductor behavior with the 1.1-eV energy gap. The KMgP in the bulk phase is a relatively good thermoelectric compound with a figure of merit of 0.7 above the room temperature. The KMgP [111] film has three K-, Mg- and P-terminations. The last one has 100% spin polarization at the Fermi level, which is referred to as the fully half-metallic behavior. The thermoelectric efficiency of the P-termination case in the up spin is more than that of the bulk structure. The figure of merit for this termination is about one at room temperature, which made it the right candidate for thermoelectric applications.