One major challenge in the next generation THz technology is to develop highly efficient, ultra-broadband and low-cost terahertz emitters with a gapless spectrum. Up-to-date, most broadband and table-top THz emitters are based on the femtosecond laser excitations, taking advantage exclusively of the charge property of the electron. Here, we introduce two types of broadband spin-based THz emitters composed of the ferromagnetic metallic heterostructures, e.g. (Co, Fe)/Pt and Fe/Ag/Bi. We have carried out detailed thickness-dependent experiments in these samples. Such investigations not only enable us to clarify the intrinsic mechanisms behind the THz radiation - the inverse spin Hall effect (ISHE) and the inverse Rashba-Edelstein effect (IREE), but also help to determine the key parameters to optimize the THz emission. The emitted THz wave, with its phase and polarization easily manipulated by changing the film stacking order and the magnetization direction, has an ultra-broadband width and strong amplitude. We also demonstrate that the THz radiation arising from both the ISHE and IREE can be selectively superimposed with each other.
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Jingbo Qi, a professor in the School of Electronic Science and Engineering at University of Electronic Science and Technology of China. He got his Ph.D. from Vanderbilt University (USA). He was ever a postdoctoral associate in the National High Magnetic Field Laboratory and Los Alamos National Laboratory, respectively. His main research interest focuses on using the ultrafast optical spectroscopy and terahertz spectroscopy to study the dynamical properties in various material systems.
联系人：陆 凌 研究员