Communications of the ACM
Magnetic Vortex Reveals Key to Spintronic Speed Limit
This color graphic, positioned above an actual image of the vortex core captured by the transmission electron microscope, shows the trapped spins moving around the permalloy sample, which then generate the conical vortex core rising out of the center.
Credit: Brookhaven National Laboratory
Brookhaven National Laboratory researchers say they have precisely measured an important parameter of electron interaction known as non-adiabatic spin torque, which is essential to the future development of spintronic devices. Their method acts as a guide for the reading and writing of digital information, as well as defines the upper limit on processing speed that could lead to a spintronic revolution. "By precisely imaging the spin orbits with a dedicated transmission electron microscope at Brookhaven, we advanced a truly fundamental understanding that has immediate implications for electronic devices," says Brookhaven Lab's Yimei Zhu.
The researchers applied a spectrum of high-frequency electric currents to a patterned film called permalloy. The material was designed to strictly contain any generated magnetic field by forcing the electrons to combine with the permalloy, and building into an observable and testable phenomenon called a magnetic vortex core. "By capturing images of this micrometer [millionth of a meter] effect, we can deduce the precise value of the non-adiabatic torque's contribution to the vortex, which plays out on the nanoscale," Zhu says.
The new measurement identifies a fundamental limit on data manipulation speeds, which can be used to develop the next generation of digital devices.
From Brookhaven National Laboratory
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Abstracts Copyright © 2012 Information Inc., Bethesda, Maryland, USA
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