[qmeso-seminar] семинар сектора 19 декабря

[Mikhail A. Skvortsov]

                     СЕМИНАР СЕКТОРА КВАНТОВОЙ МЕЗОСКОПИКИ

                         пятница 19 декабря, 15:00, ИТФ


                            E. J. Koenig (Karlsruhe)

         Half-integer quantum Hall effect of disordered Dirac fermions
                       at a topological insulator surface


The unconventional (half-integer) quantum Hall effect for a single species of Dirac fermions is analyzed. In the introduction I will discuss experimental measurements of the half-integer Hall conductance g_{xy} of topological insulator surface states and unveil its field theoretical origin. For the calculation of the conductivity tensor, the following two step procedure is applied. In the first step, semiclassical transport coefficients are derived in the case of both orbital and Zeeman coupling to an external magnetic field. In this context, I plan to give a pedagogic review of the modified Boltzmann transport theory for the anomalous Hall effect. The semiclassical conductivity tensor serves as input parameters for the second step: It consists in the renormalization group treatment of the appropriately modified non-linear sigma model and thus accounts for localization effects. The resulting phase diagram (levitation scenario) will also be discussed in this context. If time permits, I will further explain how to reconcile Laughlin\'s flux insertion argument with half-integer Hall conductance and/or present the calculation of the current density beyond linear response in the limit of smooth scalar potential.