Ultrafast photocurrents at the surface of the three-dimensional topological insulator Bi 2 Se 3
| Autor: | Gregor Mussler, Andrzej Hruban, Martin Wolf, Markus Münzenberg, Lukas Braun, Luca Perfetti, Tobias Kampfrath, Marcin Konczykowski, Thomas Schumann |
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| Přispěvatelé: | Fritz-Haber-Institut der Max-Planck-Gesellschaft (FHI), Max Planck Society, PGI-9 and JARA-FIT, Forschungszentrum Ju¨lich, 52425 Ju¨lich, Germany, Institute of Electronic Materials Technology, 01-919 Warsaw, Poland, Laboratoire des Solides Irradiés (LSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Institut für Physik [Greifswald], Ernst-Moritz-Arndt-Universität Greifswald, ANR-13-IS04-0001,IRIDOTI,Dopage par Irradiation des IsolantsTopologiques(2013) |
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
Electromagnetic field
Terahertz radiation Science General Physics and Astronomy Physics::Optics 02 engineering and technology terahertz spectroscopy 01 natural sciences Article General Biochemistry Genetics and Molecular Biology 0103 physical sciences Light beam [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat] 010306 general physics Spin-½ Physics Multidisciplinary Condensed matter physics business.industry Scattering General Chemistry Condensed Matter::Mesoscopic Systems and Quantum Hall Effect 021001 nanoscience & nanotechnology topological insulators Orders of magnitude (time) Topological insulator Optoelectronics 0210 nano-technology business Ultrashort pulse |
| Zdroj: | Nature Communications Nature Communications, Nature Publishing Group, 2016, 7, pp.13259. ⟨10.1038/ncomms13259⟩ Nature Communications, 2016, 7, pp.13259. ⟨10.1038/ncomms13259⟩ Nature Communications, Vol 7, Iss 1, Pp 1-9 (2016) |
| ISSN: | 2041-1723 |
| Popis: | Three-dimensional topological insulators are fascinating materials with insulating bulk yet metallic surfaces that host highly mobile charge carriers with locked spin and momentum. Remarkably, surface currents with tunable direction and magnitude can be launched with tailored light beams. To better understand the underlying mechanisms, the current dynamics need to be resolved on the timescale of elementary scattering events (∼10 fs). Here, we excite and measure photocurrents in the model topological insulator Bi2Se3 with a time resolution of 20 fs by sampling the concomitantly emitted broadband terahertz (THz) electromagnetic field from 0.3 to 40 THz. Strikingly, the surface current response is dominated by an ultrafast charge transfer along the Se–Bi bonds. In contrast, photon-helicity-dependent photocurrents are found to be orders of magnitude smaller than expected from generation scenarios based on asymmetric depopulation of the Dirac cone. Our findings are of direct relevance for broadband optoelectronic devices based on topological-insulator surface currents. Surface currents in topological insulators can be controlled by light, but the underlying mechanisms are not well understood. Here, Braun et al. report an ultrafast shift photocurrent at the surface of Ca-doped Bi2Se3, whereas injection currents are much smaller than expected from asymmetric depopulation of the Dirac cone. |
| Databáze: | OpenAIRE |
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