Separating the bulk and surface n- to p-type transition in the topological insulator GeBi4-xSbxTe7

Stefan Muff, Fabian Von Rohr, Gabriel Landolt, Bartosz Slomski, Andreas Schilling, Robert J. Cava, Jürg Osterwalder, J. Hugo Dil

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24 Scopus citations

Abstract

We identify the multilayered compound GeBi4Te7 to be a topological insulator with a Dirac point slightly above the valence band maximum, using angle-resolved photoemission spectroscopy (ARPES) measurements. The spin polarization satisfies the time reversal symmetry of the surface states, visible in spin-resolved ARPES. For increasing Sb content in GeBi 4-xSbxTe7 we observe a transition from n to p type in bulk sensitive Seebeck coefficient measurements at a doping of x=0.6. In surface sensitive ARPES measurements a rigid band shift is observed with Sb doping, accompanied by a movement of the Dirac point towards the Fermi level. Between x=0.8 and x=1 the Fermi level crosses the band gap, changing the surface transport regime. This difference of the n- to p-type transition between the surface region and the bulk is caused by band bending effects which are also responsible for a noncoexistence of insulating phases in the bulk and in the near surface region.

Original languageEnglish (US)
Article number035407
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume88
Issue number3
DOIs
StatePublished - Jul 3 2013

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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