Regensburg 2019 – scientific programme

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O: Fachverband Oberflächenphysik

O 96: Focus Session: Surface Transport at the Atomic Scale

O 96.7: Talk

Friday, April 5, 2019, 12:30–12:45, H15

In-situ disentangling surface state transport channels of a topological insulator thin film by gating — •Bert Voigtländer, Felix Lüpke, Sven Just, Vasily Cherepanov, and F. Stefan Tautz — Peter Grünberg Institut (PGI-3) and JARA-FIT, Forschungszentrum Jülich, 52425 Jülich, Germany

In the thin film limit, the surface state of a three-dimensional topological insulator gives rise to two parallel conduction channels at the top and bottom surface of the film, which are difficult to disentangle in transport experiments. Here, we present gate-dependent multi-tip scanning tunneling microscope transport measurements combined with photoemission experiments all performed in-situ on pristine BiSbTe3 thin films. To analyze the data, we develop a generic transport model including quantum capacitance effects. This approach allows us to quantify the gate-dependent conductivities, charge carrier concentrations, and mobilities for all relevant transport channels of three-dimensional topological insulator thin films (i.e., the two topological surface state channels, as well as the interior of the film). For the present sample, we find that the conductivity in the bottom surface state channel is minimized below a gate voltage of V = *34 V and the top surface state channel dominates the transport through the film.