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HL: Fachverband Halbleiterphysik

HL 23: Topological Insulators I (jointly with MA, DS, O, TT)

HL 23.5: Vortrag

Montag, 26. März 2012, 18:45–19:00, H 1012

Unoccupied electronic states of topological insulators — •Christian Langenkämper¹, Anna Zumbülte¹, Sune N. P. Wissing¹, Anke B. Schmidt¹, Markus Donath¹, Peter Krüger², Richard C. Hatch³, Philip Hofmann³, Kenta Kuroda⁴, Koji Miyamoto⁵, and Akio Kimura⁴ — ¹Physikalisches Institut, Westfälische Wilhelms-Universität Münster, Germany — ²Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster, Germany — ³Department of Physics and Astronomy, Aarhus University, Denmark — ⁴Graduate School of Science, Hiroshima University, Japan — ⁵Hiroshima Synchrotron Radiation Center, Hiroshima University, Japan

We report on the first investigation of the unoccupied electronic states of materials which are currently discussed in the context of topological insulators: Bi₂Se₃(111), Sb(111) and TlBiSe₂(111). First, different preparation methods (sputter-annealing, cleaving with scotch-tape) will be compared with regard to the surface quality of the samples, i.e. crystallographic order and chemical composition. Second, spin-resolved inverse-photoemission data will be presented. The experimental requirements concerning energy and momentum resolution will be addressed. Our first results show predominantly bulk-derived features with only small spin asymmetries. The experimental data will be discussed along with theoretical calculations for the unoccupied states.