[qmeso-seminar] семинар сектора 7 июня (ЧЕТВЕРГ!)

[Mikhail A. Skvortsov]

                     СЕМИНАР СЕКТОРА КВАНТОВОЙ МЕЗОСКОПИКИ

                  четверг 7 июня, 11:30, ИФП им. П. Л. Капицы

      Elio Koenig (Karlsruhe Institute of Technology, Karlsruhe, Germany)

    Interaction and disorder effects in 3D topological insulator thin films

It has been recently predicted that Coulomb interaction drives a surface
of a 3D topological insulator into a critical state (Ostrovsky et al., PRL
105, 036803 (2010)). We employ the sigma-model formalism to investigate the
effect of electron-electron interaction on the transport by surface states
in topological insulator thin films. We take into account the interaction
of electrons on different surfaces and also the top-bottom asymmetry of the
film (different densities of states and strength of disorder on top/bottom
surface). This asymmetry is naturally present in experiments where the
electronic densities on the surfaces are controlled independently by means
of electrostatic gates. The lack of symmetry between top and bottom
surfaces is shown to have strong effect on the film conductivity. The
interplay of weak antilocalization, Coulomb interaction within and between
surfaces and topological protection leads to a rich flow diagram
representing the low temperature behavior of the system. In particular, the
intersurface interaction is found to evoke a non-monotonic temperature
dependence of the conductuctivity and eventually drives the film into a
metallic state. The connection with recent experiments on Bi_2Se_3 films is
discussed.