Effect ofp1/2corrections in the electronic structure ofBi2

Abstract

Unlike other relativistic corrections to the Schrödinger equation, such as the Darwin, mass-velocity, and spin-orbit interactions ͑SOI͒, the p 1/2 corrections do not arise from expansion of the relativistic Dirac equation. Rather, these corrections relate to the way in which the p-orbital wave functions are expanded in density functional calculations with SOI. A test of this correction is necessary in a strongly bonded system which has significant SOI effects, such as Bi 2 Te 3 . Previous electronic structure calculations of Bi 2 Te 3 have disagreed about the position of the conduction band minimum ͑CBM͒. While de Haas-van Alphen experiments find the CBM to have sixfold degeneracy, most previous calculations have found this minimum to lie at a twofold degenerate point. A recent paper found the correct degeneracy, but was unable to explain the difference in their and previous results. We find the correct degeneracy by taking into account the p 1/2 corrections, which shifts the minimum from a twofold degenerate point to a sixfold degenerate point and is necessary for the correct degeneracy of the valence band as well. The p 1/2 corrections for the Sb 5p states are much weaker, explaining the electronic structure results in the related compounds Sb

Room-temperature MBE deposition, thermoelectric properties, and advanced structural characterization of binary Bi2Te3 and Sb2Te3 thin films

“…For n-type Bi 2 Te 3 the effective masses associated with the conduction band are by factor of 1.4 smaller as compared to the effective masses associated with the valence band of p-type Bi 2 Te 3 [31,32]. Band structure calculations confirmed these experimental findings [33][34][35]. Therefore, larger charge carrier mobilities were expected for n-type Bi 2 Te 3 thin films as compared to p-type Bi 2 Te 3 bulk.…”

Half-Heusler topological insulators: A first-principles study with the Tran-Blaha modified Becke-Johnson density functional

“…Wave functions and potentials inside the atomic sphere are expanded in spherical harmonics up to l = 10 and 4, respectively. Spin-orbit coupling is included by a second-variational procedure 25 , where states up to 9 Ry above fermi level are included in the basis expansion, and the relativistic p 1/2 corrections were also considered for 5p and 6p orbit in order to improve the accuracy 27 . Table I.…”

Substantial pressure effect on the resistivity and Curie temperature for the diluted magnetic semiconductor Sb2–xVxTe3

“…A background free hole concentration of 1 × 10 20 cm -3 arising from native antisite defects is typical for pure Sb 2 Te 3 , and doping with vanadium does not alter the carrier concentration. The valence band of the host semiconductor is multi-valley [10,11] and there is evidence from Shubnikov-de Haas data that both an upper, light hole and lower, heavy hole band are populated for these high hole densities [12]. The pressure dependence of electrical resistivity in Sb 2 Te 3 [13] and isostructural Bi 2 Te 3 [14] has been investigated previously, and resistivity was found to be significantly reduced upon application of high pressures.…”