5/21/2023 0 Comments Two worlds 3 on the way![]() ![]() As a result, the terahertz wave has no chance of transferring its energy specifically and directly to a much slower spin wave. ![]() And while terahertz waves have a wavelength of slightly less than a millimeter, the wavelength of spin waves, on the other hand, is in the range of only a few nanometers. Their propagation speed is hundreds of times slower than that of light. Terahertz waves travel as electromagnetic radiation at the speed of light, while spin waves are tied to the existence of interacting spins. But there is a problem along the way: the completely different speed of the two wave phenomena. Magnons and terahertz photons have the same energies and should therefore be easily convertible into each other. Similar to light, which can also be described in terms of individual particles called photons, the energies of spin waves are quantized, and the quanta of spin waves are called magnons. Problem: Communication between different types of waves Coupling optical terahertz technology with spin-based devices could therefore enable completely new and efficient concepts for IT technologies. This is exactly the target range for novel ultrafast technologies for data transmission and processing. So, unlike in today's computer chips, there are no heat losses due to currents in spin-based devices.Ĭonveniently, the characteristic frequencies of the high-energy spin waves are in the terahertz range. 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. This is interesting because a spin wave - like any wave - can be used as an information carrier. 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. And like a gyroscope, an external perturbation can tilt the spin's axis of rotation: A gyroscopic motion, called precession, follows suit. Electrons have an effective spin which behaves like a spinning top. Sergey Kovalev of the Institute of Radiation Physics at HZDR, where the experiments were conducted. "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. ![]()
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