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Separating the bulk and surface n- to p-type transition in the topological insulator GeBi_{4−x}Sb_{x}Te_{7}


Muff, Stefan; von Rohr, Fabian; Landolt, Gabriel; Slomski, Bartosz; Schilling, Andreas; Cava, Robert J; Osterwalder, Jürg; Dil, J Hugo (2013). Separating the bulk and surface n- to p-type transition in the topological insulator GeBi_{4−x}Sb_{x}Te_{7}. Physical Review B, 88(3):035407.

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 GeBi4−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.

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 GeBi4−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.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Physics Institute
Dewey Decimal Classification:530 Physics
Language:English
Date:2013
Deposited On:09 Dec 2013 09:25
Last Modified:05 Apr 2016 17:13
Publisher:American Physical Society
ISSN:1098-0121
Publisher DOI:https://doi.org/10.1103/PhysRevB.88.035407

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