Influence of electron-phonon coupling on the pressure-induced topological phase transition in BiTeI

Topological phase transitions are closely related to the bulk electronic bandstructure, which varies with temperature. This variation is a consequence of electron-phonon interactions, which induce a shift in the electronic band energies that may promote or suppress the topologically non-trivial phase. When studying tunable topological phase transitions in real materials, the value of the critical parameter may therefore change with temperature. Understanding the effect of temperature on these phase transitions is thus crucial in designing real devices intended to work in various conditions. We investigate the temperature dependence of the pressure-induced topological phase transition in three-dimensional crystalline BiTeI through first principles methods. We compute the electron-phonon coupling and the electronic bandstructure using density functional perturbation theory (DFPT). We also study the behavior of the narrow intermediate Weyl semimetal phase that has been theoretically predicted for this material, to evaluate if it could be observed experimentally.