Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 2: Topological insulators: mostly structure and electronic structure (with MA/O/TT)

HL 2.3: Vortrag

Montag, 31. März 2014, 10:00–10:15, POT 051

Temperature-dependent surface band gap of Dirac fermions observed at the (111) surface of the crystalline topological insulator Pb-Sn-Se — •Partha S. Mandal1, Gunther Springholz2, Günther Bauer2, Valentine V. Volobuev2, Andrei Varykhalov1, Oliver Rader1, and Jaime Sánchez-Barriga11Helmholtz-Zentrum Berlin — 2Johannes-Kepler-Universität Linz

Using angle-resolved photoemission, we studied (111)-oriented epitaxial films of Pb-Sn-Se grown by molecular beam epitaxy. The topological-to-trivial-insulator phase transition [1] is monitored probing the bulk valence band as a function of Sn concentration and temperature between 30 K and room temperature. In the topological phase, the topological surface state opens a band gap indicating a mass aquisition that is not caused by broken time reversal symmetry. We discuss this phenomenon in comparison to conventional topological insulators [2] protected by time-reversal symmetry.

[1] P. Dziawa, B. J. Kowalski, K. Dybko, R. Buczko, A. Szczerbakow, M. Szot, E. Łusakowska, T. Balasubramanian, B. M. Wojek, M. H. Berntsen, O. Tjernberg, T. Story, Nature Mat. 11, 1023 (2012).

[2] T. Sato, K. Segawa, K. Kosaka, S. Souma, K. Nakayama, K. Eto, T. Minami, Y. Ando, and T. Takahashi, Nature Phys. 7, 840 (2011).

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