Nernst-ettingshausen tensor in Sb2Te3 single crystal

Abstract

On one Sb2Te3 single crystal, the temperature dependences of all three independent components of the Nernst-Ettingshausen tensor (Qikl) are measured in the temperature range of 85–450 K, all three components being negative. Alongside with the Nernst-Ettingshausen effect, the anisotropy of the Hall (Rikl) and Seebeck (Sij) coefficients and the conductivity (σii) is also investigated. The carried-out analysis of the experimental data on the Nernst-Ettingshausen and Seebeck effects indicates that there is the mixed scattering mechanism with the participation of acoustic phonons and impurity ions, the relative contributions of these mechanisms varying with temperature. In the relaxation-time-tensor approximation, the values of the effective scattering parameter (r) are determined. The obtained values point to the dominant scattering at acoustic phonons in the cleavage plane and to the substantial contribution of charged ions to the scattering along the trigonal axis c3. It is shown that it is possible to explain the major features of experimental data on the Nernst-Ettingshausen effect within the two-valence-band model with the participation of several groups of holes in the transport phenomena.