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

Publication date2013-07-03
First online date2013-07-03
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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Citation (ISO format)
MUFF, Stefan et al. Separating the bulk and surface <i>n</i>-to <i>p</i>-type transition in the topological insulator GeBi<sub>4−x</sub>Sb<sub>x</sub>Te<sub>7</sub>. In: Physical review. B, Condensed matter and materials physics, 2013, vol. 88, n° 3, p. 035407. doi: 10.1103/PhysRevB.88.035407
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ISSN of the journal1098-0121
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