Muff, Stefanvon Rohr, FabianLandolt, GabrielSlomski, BartoszSchilling, AndreasCava, Robert J.Osterwalder, JuergDil, J. Hugo2015-06-232015-06-232015-06-23201310.1103/PhysRevB.88.035407https://infoscience.epfl.ch/handle/20.500.14299/115349WOS:000321270200003We 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.text::journal::journal article::research article