Work

Fermi surface evolution of Na-doped PbTe studied through density functional theory calculations and Shubnikov–de Haas measurements

Year: 2016

Type: article

Abstract: Lead telluride (PbTe) is a widely known thermoelectric material and a narrow-gap semiconductor. The introduction of impurity dopants in this compound has shown to significantly increase the thermoelectric figure of merit, and for certain dopants, to even lead the material to a superconducting ground state. Understanding the physical origin of these enhanced properties and their dependence on the choice of dopant chemistry requires a detailed knowledge of the electronic structure, in particular its evolution with carrier concentrations. With this in mind, the authors of this paper present a combined experimental and first-principles study of the evolution of the low-temperature Fermi surface of Na-doped PbTe. Their Shubnikov--de Haas measurements allowed the determination of the full morphology of the Fermi surface for hole concentrations one order of magnitude higher than other previous studies in this material, showing that the band dispersion is consistent with a nonparabolic single-band Kane-model dispersion, in which the hole-pockets are ellipsoids of fixed anisotropy throughout the band, but the effective masses depend strongly on Fermi energy. Additionally, the authors show that standard density functional calculations underestimate the energy difference between the first two valence-band maxima, since their experimental data is consistent with a single-band Fermi surface over the entire doping range studied.

Source: Physical review. B./Physical review. B

DOI: 10.1103/physrevb.94.195141