The electronic band structure of Pb1-xSnxTe alloys. II. Temperature dependence through the structural and band inversion transitions

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Abstract
For pt.I see ibid., vol.15, p.317 (1985). The Shubnikov-de Haas effect has been studied in samples of Pb1-xSnxTe which have normal or inverted band configurations at low temperatures. The measurements have been made over a range of temperatures which take the samples through the structural phase transition from the rhombohedral to the cubic rock-salt phase. The changes in Fermi-surface cross-sectional areas with temperature are interpreted in terms of a temperature-dependent band-structure calculation which includes the interaction between electrons and soft transverse optic phonons associated with the phase transition and the temperature-dependent sublattice displacement and shear strain in the rhombohedral phase. The basic band-structure parameters are those deduced from the orientation-dependent study of Pb1-xSnxTe at 4.2K in the distorted phase, and the variations with temperature of the energy gap in the alloys is used to yield further parameters. The resulting fit to the variation of the cross-sectional area with temperature is excellent. Measurements of the temperature dependence of the transverse effective mass have also been made in this temperature range and it is found that a temperature-dependent scattering parameter has to be included in the theory to obtain agreement with the observations. This parameter is related to the soft-TO phonon scattering and to the formation of domain walls near the transition.