https://www.sciencedaily.com/releases/2023/01/230131101902.htm > "We were able to efficiently excite high-energy spin waves using terahertz light in a sandwich-like material system consisting of two metal films a few nanometers thick, with a ferromagnetic layer sandwiched in between," says Dr. Sergey Kovalev of the Institute of Radiation Physics at HZDR, where the experiments were conducted. Electrons have an effective spin which behaves like a spinning top. And like a gyroscope, an external perturbation can tilt the spin's axis of rotation: A gyroscopic motion, called precession, follows suit. In ferromagnetic materials, there is a very strong interaction between the electron spins, and as a result, a precession started locally continues in the form of a spin wave throughout the ferromagnetic material layer. This is interesting because a spin wave -- like any wave -- can be used as an information carrier. While each electron spin is in motion, in the ferromagnets considered it remains in its position in the atomic lattice, therefore no current flow is involved. So, unlike in today's computer chips, there are no heat losses due to currents in spin-based devices. > Conveniently, the characteristic frequencies of the high-energy spin waves are in the terahertz range. This is exactly the target range for novel ultrafast technologies for data transmission and processing. Coupling optical terahertz technology with spin-based devices could therefore enable completely new and efficient concepts for IT technologies.