Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 53: Transport: Topological Insulators 3 (jointly with TT, MA)
HL 53.2: Vortrag
Mittwoch, 28. März 2012, 09:45–10:00, BH 334
Topological insulators in magnetic fields: Quantum Hall effect and edge channels with non-quantized θ-term — •Matthias Sitte1, Achim Rosch1, Ehud Altman2, and Lars Fritz1 — 1Institute for Theoretical Physics, University of Cologne, Cologne, Germany — 2Department of Condensed Matter Physics, The Weizmann Institute of Science, 76100 Rehovot, Israel
We investigate how a magnetic field induces one-dimensional edge channels when the two-dimensional surface states of three-dimensional topological insulators become gapped. The Hall effect, measured by contacting those channels, remains quantized even in situations, where the θ-term in the bulk and the associated surface Hall conductivities, σxy, are not quantized due to the breaking of time-reversal symmetry. The quantization arises as the θ-term changes by ± 2 π n along a loop around n edge channels. Model calculations show how an interplay of orbital and Zeeman effects leads to quantum Hall transitions, where channels get redistributed along the edges of the crystal. The network of edges opens new possibilities to investigate the coupling of edge channels.
M. Sitte, A. Rosch, E. Altman, and L. Fritz, arXiv:1110.1363