Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 51: Topological Insulators II (jointly with MA, DS, O, TT)

HL 51.2: Talk

Wednesday, March 28, 2012, 09:45–10:00, EB 301

Probing the topological states of Sb₂Te₃ by spin polarized photoemission spectroscopy — •Christian Pauly¹, Gustav Bihlmayer², Marcus Liebmann¹, Dinesh Subramaniam¹, Martin Grob¹, Alexander Georgi¹, Markus Scholz³, Jaime Sanchez Barriga³, Stefan Blügel², Oliver Rader³, and Markus Morgenstern¹ — ¹II. Physikalisches Institut B, RWTH Aachen University and JARA-FIT, Germany — ²Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA-FIT, Germany — ³Helmholtz-Zentrum für Materialien und Energie, Berlin, Germany

Using high resolution spin- and angle-resolved photoemission spectroscopy, we map the electronic structure and spin texture of the surface states of the topological insulator Sb₂Te₃. Similar to the well explored Bi₂Te₃ and Bi₂Se₃ which possess TI properties with the most simple electronic structure [1], we directly show that Sb₂Te₃ exhibits Z₂ topological properties with a single spin-Dirac cone at the Γ-point. In addition, a strongly spin-orbit split surface state is observed at lower energy. In Γ-K direction, the band is located within a spin-orbit gap, governing the energy position of the state. In combination with DFT calculation, we provide direct evidence for an argument given by Pendry [2], that there must be at least one surface state inside a SO gap, if the gap is located in the zone. Thus, similar to the topological state, this state is protected by symmetry. [1] H. Zhang et al., Nature Phys. 5, 438 (2009) [2] J. B. Pendry et al., Surf. Sci. 49, 87 (1975)