Terahertz wave emission from the trigonal layered PtBi2

Comprehensive study of the ultrafast photoexcited carrier dynamics in Sb2Te3–GeTe superlattices

“…the THz radiation can be fitted well by cos 2β , which is consist with the shift current mechanism. [37,39] different processes, which can be fitted by the phenomenological expression [45,[48][49][50] E THz,x (α,t)…”

“…We also observe the shift current generated by the linear photo-galvanic effect (LPGE) and the injection current generated by the circular photo-galvanic effect (CPGE) in Sb 2 Te 3 -GeTe superlattices, which depend on the topological state with spin-momentum locking. [37][38][39] It can be found that, by decreasing the thickness of GeTe and Sb 2 Te 3 layers, and increasing the number of GeTe and Sb 2 Te 3 layers, the interlayer coupling can be enhanced, which significantly reduces the CPGE contribution. Further, utilizing transient reflectance spectroscopy, a photoinduced bleaching is observed at the wavelength of ∼ 1100 nm to ∼ 1400 nm, demonstrating a bandgap at ∼ 1.0 eV above the Fermi level.…”

Hot Carrier Localization Affected by A Cations in Hybrid Perovskite

“…Therefore, the photon drag current contains the information on the photon-carrier-phonon interaction and is highly sensitive to the carrier excess energy, band structure, and electron-phonon interaction. Meanwhile, transient delocalization currents induced by light pulses can be captured by terahertz emission spectroscopy in photoelectric material 17,18 . Notably, the prerequisite for the existence of second-order nonlinear effects is to break the central symmetry of the system 18,19 , which limits a wide range of centrosymmetric material applications, for example, polycrystalline perovskite thin films.…”