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TT: Fachverband Tiefe Temperaturen

TT 103: Transport: Poster Session

TT 103.43: Poster

Donnerstag, 19. März 2015, 15:00–18:00, Poster B

Individual tuning of the top and bottom surface states on a three dimensional topological insulator — •David Mahler, Jonas Wiedenmann, Cornelius Thienel, Kalle Bendias, Christopher Ames, Christoph Brüne, Hartmut Buhmann, and Laurens W. Mohlenkamp — Experimentelle Physik 3, Institut für Physik und Astronomie, Universität Würzburg

It has been shown, that the semimetal HgTe grown on a CdTe substrate becomes a three dimensional topological insulator due to its inverted band structure and the strain induced band gap of approximately 20 meV [1]. By using a top gate the dominance of the surface states in magneto transport data over a wide density range was observed and has been explained by the Dirac-screening of the surface states [2].

We demonstrate that the introduction of a back gate created by epitaxial growth on an n-doped gallium arsenide substrate allows us to independently change the occupation of the upper and lower surface state. This can be shown by transport measurements at low temperatures and high magnetic fields. Therefore the occupation of the upper and lower surface state can be varied by the applied top and back gate voltages leading to different quantum hall sequences.

[1] C. Brüne et al., Phys. Rev. Lett. 106, 126803 (2011).

[2] C. Brüne et al., PRX to be published.