Terahertz signatures of ultrafast Dirac fermion relaxation at the surface of topological insulators

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 cha...

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Detalles Bibliográficos
Autores: Kovalev, Sergey|||0000-0002-2290-1016, Tielrooij, Klaas-Jan|||0000-0002-0055-6231, Deinert, Jan-Christoph|||0000-0001-6211-0158, Ilyakov, Igor|||0000-0002-5928-7996, Awari, Nilesh, Chen, Min|||0000-0001-5230-360X, Ponomaryov, Alexey N., Bawatna, Mohammed|||0000-0002-2382-3363, de Oliveira, T.V.A.G., Eng, Lukas, Kuznetsov, Kirill|||0000-0001-6075-7628, Safronenkov, D.A., Kitaeva, Galiya|||0000-0002-4860-9937, Kuznetsov, P.I., Hafez, Hassan A., Turchinovich, Dmitry|||0000-0003-0054-7092, Gensch, Michael
Tipo de recurso: artículo
Fecha de publicación:2021
País:España
Institución:Universitat Autònoma de Barcelona
Repositorio:Dipòsit Digital de Documents de la UAB
Idioma:inglés
OAI Identifier:oai:ddd.uab.cat:268445
Acceso en línea:https://ddd.uab.cat/record/268445
https://dx.doi.org/urn:doi:10.1038/s41535-021-00384-9
Access Level:acceso abierto
Palabra clave:Topological insulators
Ultrafast photonics
Descripción
Sumario: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.

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