Terahertz signatures of ultrafast Dirac fermion relaxation at the surface of topological insulators
Kovalev, Sergey (Helmholtz-Zentrum Dresden-Rossendorf)
Tielrooij, Klaas-Jan (Institut Català de Nanociència i Nanotecnologia)
Deinert, Jan-Christoph (Helmholtz-Zentrum Dresden-Rossendorf)
Ilyakov, Igor (Helmholtz-Zentrum Dresden-Rossendorf)
Awari, Nilesh (Helmholtz-Zentrum Dresden-Rossendorf)
Chen, Min (Helmholtz-Zentrum Dresden-Rossendorf)
Ponomaryov, Alexey N. (Helmholtz-Zentrum Dresden-Rossendorf)
Bawatna, Mohammed (Helmholtz-Zentrum Dresden-Rossendorf)
de Oliveira, T.V.A.G. (Technische Universität Dresden)
Eng, Lukas (Technische Universität Dresden)
Kuznetsov, Kirill (Lomonosov Moscow State University)
Safronenkov, D.A. (Lomonosov Moscow State University)
Kitaeva, Galiya (Lomonosov Moscow State University)
Kuznetsov, P.I. (Kotelnikov IRE RAS)
Hafez, Hassan A. (Universität Bielefeld. Fakultät für Physik)
Turchinovich, Dmitry (Universität Bielefeld. Fakultät für Physik)
Gensch, Michael (Technische Universität Berlin)

Date:	2021
Abstract:	Topologically protected surface states present rich physics and promising spintronic, optoelectronic, and photonic applications that require a proper understanding of their ultrafast carrier dynamics. Here, we investigate these dynamics in topological insulators (TIs) of the bismuth and antimony chalcogenide family, where we isolate the response of Dirac fermions at the surface from the response of bulk carriers by combining photoexcitation with below-bandgap terahertz (THz) photons and TI samples with varying Fermi level, including one sample with the Fermi level located within the bandgap. We identify distinctly faster relaxation of charge carriers in the topologically protected Dirac surface states (few hundred femtoseconds), compared to bulk carriers (few picoseconds). In agreement with such fast cooling dynamics, we observe THz harmonic generation without any saturation effects for increasing incident fields, unlike graphene which exhibits strong saturation. This opens up promising avenues for increased THz nonlinear conversion efficiencies, and high-bandwidth optoelectronic and spintronic information and communication applications.
Grants:	European Commission 804349 European Commission 737038 Ministerio de Economía y Competitividad SEV-2017-0706
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Topological insulators ; Ultrafast photonics
Published in:	npj Quantum Materials, Vol. 6 (2021) , art. 84, ISSN 2397-4648

DOI: 10.1038/s41535-021-00384-9

6 p, 1.0 MB

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Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > Catalan Institute of Nanoscience and Nanotechnology (ICN2)
Articles > Research articles
Articles > Published articles