Institute of Fundamental Technological Research

The temperature renormalization of the bulk band structure of a topological crystalline insulator, SnTe, is calculated using first-principles methods. We explicitly include the effect of thermal-expansion-induced modification of electronic states and their band inversion on electron-phonon interaction.We show that the direct gap decreases with temperature, as both thermal expansion and electron-phonon interaction drive SnTe towards the phase transition to a topologically trivial phase as temperature increases. The band gap renormalization due to electron-phonon interaction exhibits a nonlinear dependence on temperature as the material approaches the phase transition, while the lifetimes of the conduction band states near the band edge show a nonmonotonic behawior with temperature. These effects should have important implications on bulk electronic and thermoelectric transport in SnTe and other topological insulators.