Ultrafast helicity control of surface currents in topological insulators with near-unity fidelity

In recent years, a class of solid state materials, called three-dimensional topological insulators, has emerged. In the bulk, a topological insulator behaves like an ordinary insulator with a band gap. At the surface, conducting gapless states exist showing remarkable properties such as helical Dira...

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Bibliographic Details
Published in:arXiv.org 2015-01
Main Authors: Kastl, Christoph, Karnetzky, Christoph, Karl, Helmut, Holleitner, Alexander W
Format: Article
Language:English
Subjects:
Backscattering
Circular polarization
Cryogenic temperature
Current carriers
Helicity
Optoelectronic devices
Polarized light
Topological insulators
Topology
Unity
Veal
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Summary:In recent years, a class of solid state materials, called three-dimensional topological insulators, has emerged. In the bulk, a topological insulator behaves like an ordinary insulator with a band gap. At the surface, conducting gapless states exist showing remarkable properties such as helical Dirac dispersion and suppression of backscattering of spin-polarized charge carriers. The characterization and control of the surface states via transport experiments is often hindered by residual bulk contributions yet at cryogenic temperatures. Here, we show that surface currents in Bi2Se3 can be controlled by circularly polarized light on a picosecond time scale with a fidelity near unity even at room temperature. We re-veal the temporal separation of such ultrafast helicity-dependent surface currents from photo-induced thermoelectric and drift currents in the bulk. Our results uncover the functionality of ultrafast optoelectronic devices based on surface currents in topological insulators.
ISSN:2331-8422
DOI:10.48550/arxiv.1501.07784