Dirac-screening stabilized surface-state transport in a topological insulator

Christoph Brüne, Cornelius Thienel, Michael Stuiber, Jan Böttcher, Hartmut Buhmann, Elena G. Novik, Chao Xing Liu, Ewelina M. Hankiewicz, Laurens W. Molenkamp

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41 Scopus citations

Abstract

We report magnetotransport studies on a gated strained HgTe device. This material is a threedimensional topological insulator and exclusively shows surface-state transport. Remarkably, the Landaulevel dispersion and the accuracy of the Hall quantization remain unchanged over a wide density range (3 × 1011 cm-2 < n < 2 × 1012 cm-2). These observations imply that even at large carrier densities, the transport is surface-state dominated, where bulk transport would have been expected to coexist already. Moreover, the density dependence of the Dirac-type quantum Hall effect allows us to identify the contributions from the individual surfaces. A k · p model can describe the experiments but only when assuming a steep band bending across the regions where the topological surface states are contained. This steep potential originates from the specific screening properties of Dirac systems and causes the gate voltage to influence the position of the Dirac points rather than that of the Fermi level.

Original languageEnglish (US)
Article number041045
JournalPhysical Review X
Volume4
Issue number4
DOIs
StatePublished - 2014

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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