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.
Description
Terahertz signatures of ultrafast Dirac fermion relaxation at the surface of topological insulators | npj Quantum Materials
%0 Journal Article
%1 noauthororeditor
%A Kovalev, S.
%A Tielrooij, K.-J.
%A Deinert, J.-C.
%A Ilyakov, I.
%A Awari, N.
%A Chen, M.
%A Ponomaryov, A.
%A Bawatna, M.
%A de Oliveira, T. V. A. G.
%A Eng, L. M.
%A Kuznetsov, K. A.
%A Safronenkov, D. A.
%A Kitaeva, G. Kh.
%A Kuznetsov, P. I.
%A Hafez, H. A.
%A Turchinovich, D.
%A Gensch, M.
%D 2021
%J npj Quantum Mater.
%K a
%P 84
%R 10.1038/s41535-021-00384-9
%T Terahertz signatures of ultrafast Dirac fermion relaxation at the surface of topological insulators
%U https://www.nature.com/articles/s41535-021-00384-9
%V 6
%X 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.
@article{noauthororeditor,
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.},
added-at = {2023-01-15T21:35:03.000+0100},
author = {Kovalev, S. and Tielrooij, K.-J. and Deinert, J.-C. and Ilyakov, I. and Awari, N. and Chen, M. and Ponomaryov, A. and Bawatna, M. and de Oliveira, T. V. A. G. and Eng, L. M. and Kuznetsov, K. A. and Safronenkov, D. A. and Kitaeva, G. Kh. and Kuznetsov, P. I. and Hafez, H. A. and Turchinovich, D. and Gensch, M.},
biburl = {https://www.bibsonomy.org/bibtex/25b5f77837f2b2880a5de8eb4b5a58c72/ctqmat},
day = 01,
description = {Terahertz signatures of ultrafast Dirac fermion relaxation at the surface of topological insulators | npj Quantum Materials},
doi = {10.1038/s41535-021-00384-9},
interhash = {cc4a98192590622fabcc5d3d8679ad63},
intrahash = {5b5f77837f2b2880a5de8eb4b5a58c72},
journal = {npj Quantum Mater.},
keywords = {a},
month = {10},
pages = 84,
timestamp = {2023-01-16T14:49:29.000+0100},
title = {Terahertz signatures of ultrafast Dirac fermion relaxation at the surface of topological insulators},
url = {https://www.nature.com/articles/s41535-021-00384-9},
volume = 6,
year = 2021
}