After a brief introduction to topological insulators, I will talk about topological phase transition in intrinsically nontopological materials. In particular, I will show that electron-phonon interactions can induce topological phases in direct and narrow-gap Dirac insulators. The underlying mechanism for this effect can be explained in terms of the electron-phonon scattering matrix elements, which show a peculiar dependence on the sign of the mass of the Dirac fermions. A similar mechanism applies to weak Coulomb interactions and spin-independent disorder; however, the influence of these on band topology is largely independent of temperature. Finally, I will discuss possible experimental implications of this effect in HgTe/CdTe quantum wells and Bi Tl (S_x Se_{1-x})_2.


Seminar, April 13, 2015, 12:00. Seminar Room

Hosted by Prof. Darrick Chang