Valence‐Band Properties of Bi2Te3 from Galvanomagnetic Measurements

Abstract

AbstractGalvanomagnetic effects in Bi2Te3 are investigated in magnetic fields up to 38 kOe at 1.6 and 4.2 °K on six single‐crystal samples with hole concentrations between 1.4 × 1018 and 2.4 × 1019 cm−3. A proper arbitrary‐field theory is developed for highly degenerated p‐ or n‐type Bi2Te3 on the basis of a six‐ellipsoid Drabble‐Wolfe model (DM). In accordance with Shubnikov‐de Haas oscillations, the experimental data in the concentration range over 3 to 4 × 1018 cm−3 exhibit considerable deviations from a simple DW behaviour. Using an extension of the galvanomagnetic theory to the case of two six‐ellipsoidal subbands, a good fit with the data is obtained, which do not fit to the DW description. However, a test two‐band estimate in terms of the calculated concentrations and density of states masses results in a too narrow energy gap between the subbands in the 7.1 × 1018 cm−3 sample (an order of magnitude lower than the chemical potential). The upper subband should populated at hole concentrations of the order 1017 cm−3, in contradiction to the threshold concentration of 3 to 4 × 1018 cm−3, which has been obtained in the high‐field analysis of the whole series of samples investigated.