Small Magnets: Wide-Ranging Impact on Information Technology
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Physicists have identified a microscopic process of electron spin dynamics in nanoparticles that could impact the design of applications in medicine, quantum computation, and spintronics.
Magnetic nanoparticles and nanodevices have several applications in medicine -- such as drug delivery and MRI -- and information technology. Controlling spin dynamics -- the movement of electron spins -- is key to improving the performance of such nanomagnet-based applications.
"This work advances our understanding of spin dynamics in nanomagnets," said Igor Barsukov, an assistant professor in the Department of Physics and Astronomy and lead author of the study that appears today in Science Advances.
Electron spins, which precess like spinning tops, are linked to each other. When one spin begins to precess, the precession propagates to neighboring spins, which sets a wave going. Spin waves, which are thus collective excitations of spins, behave differently in nanoscale magnets than they do in large or extended magnets. In nanomagnets, the spin waves are confined by the size of the magnet, typically around 50 nanometers, and therefore present unusual phenomena.
In particular, one spin wave can transform into another through a process called "three magnon scattering," a magnon being a quantum unit of a spin wave. In nanomagnets, this process is resonantly enhanced, meaning it is amplified for specific magnetic fields.
Source: https://www.sciencedaily.com/releases/2019/10/191025145304.htm
Journal Reference: Barsukov, H. K. Lee, A. A. Jara, Y.-J. Chen, A. M. Gonialves, C. Sha, J. A. Katine, R. E. Arias, B. A. Ivanov, I. N. Krivorotov. Giant nonlinear damping in nanoscale ferromagnets. Science Advances, 2019; 5 (10): eaav6943 DOI: 10.1126/sciadv.aav6943
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