Abstract-Broadband THz radiation via the inverse spin Hall and Rashba-Edelstein effects (Conference Presentation)

Jingbo Qi

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10732/107323I/Broadband-THz-radiation-via-the-inverse-spin-Hall-and-Rashba/10.1117/12.2322834.short

One major challenge in the next generation THz (1012) 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 novel types of broadband spin-based THz emitters composed of the ferromagnetic metallic heterostructures [1-4], 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 (~0.1-20 THz) and strong amplitude (comparable to the conventional nonlinear crystals). We also demonstrate that the THz radiation arising from both the ISHE and IREE can be selectively superimposed with each other. [1] Seifert, T. et al. Efficient metallic spintronic emitters of ultrabroadband terahertz radiation. Nat. Photon. 10, 483 (2016). [2] Yang, D. et al. Powerful and Tunable THz Emitters Based on the Fe/Pt Magnetic Heterostructure. Adv. Opt. Mater. 4, 1944 (2016). [3] Wu, Y. et al. High-performance THz emitters based on ferromagnetic/nonmagnetic heterostructures. Adv. Mater. 29, 1603031 (2017). [4] Zhou. C et al. Broadband terahertz generation via the interface inverse Rashba-Edelstein effect (submitted).