Phonon-induced topological insulating phases in group IV-VI semiconductors

Development of topological insulating phases in IV-VI compounds under dynamic lattice deformations is studied using first-principles methods. Unlike the static state of topological phases at equilibrium conditions, we show that non-trivial topological phases are induced in the compounds by the dynamic lattice deformations from selective phonon modes. Calculations of the time-reversal polarization show that the Z2 invariant of the compounds is flipped by the atomic displacements of selective phonon modes and that the compounds exhibit oscillating topological phases upon dynamic lattice deformations. Our results indicate that the elementary excitations in solids can trigger topological phases in trivial band insulators.