Ultrafast light-induced THz switching in exchange-biased Fe/Pt spintronic heterostructure

Abstract

The ultrafast optical control of magnetization in spintronic structures enables one to access to the high-speed information processing, approaching the realm of terahertz (THz). Femtosecond visible/near-infrared laser-driven ferromagnetic/nonmagnetic metallic spintronic heterostructures-based THz emitters combine the aspects from the ultrafast photo-induced dynamics and spin-charge inter-conversion mechanisms through the generation of THz electromagnetic pulses. In this Letter, we demonstrate photoexcitation density-dependent induced exchange-bias tunability and THz switching in an annealed Fe/Pt thin-film heterostructure, which otherwise is a widely used conventional spintronic THz emitter. By combining the exchange-bias effect along with THz emission, the photo-induced THz switching is observed without any applied magnetic field. These results pave the way for an all-optical ultrafast mechanism to exchange-bias tuning in spintronic devices for high-density storage, read/write magnetic memory applications.