Theory of anomalous resistivity associated with structural phase transitions in IV-VI compounds

A theoretical description of electrical-resistivity anomalies associated with structural phase transitions of IV-VI compound semiconductors is presented, taking account of interband electron—soft-TO-phonon scattering. The sublattice displacement and rhombohedral strain in the low-temperature phase are calculated within the framework of a self-consistent mean-field theory, with emphasis on the effect of electron-phonon couplings. The resistivity due to the scattering of free carriers from acoustic phonons and optic phonons is examined, including the carrier transfer among the four valleys due to valley splitting below the transition temperature ($T_c$). The theoretical calculations of electrical resistivity as well as order parameters are in good accord with data on $p$-type SnTe at the quantitative level.