Science Daily October 20, 2021
An international team of researchers (Germany, Spain, Russia) investigated the ultrafast carrier dynamics in topological insulators (TIs) of the bismuth and antimony chalcogenide family, where they isolated 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. They identified distinctly faster relaxation of charge carriers in the topologically protected Dirac surface states, compared to bulk carriers and they observed THz harmonic generation without any saturation effects for increasing incident fields, unlike graphene which exhibits strong saturation. This opens promising avenues for increased THz nonlinear conversion efficiencies, and high-bandwidth optoelectronic and spintronic information and communication applications…read more. Open Access TECHNICAL ARTICLEÂ
Transient reflectivity spectroscopy. Credit: npj Quantum Materials volume 6, Article number: 84 (2021)Â