that have been seen in a variety of media. (They first were observed in a boat canal in 1834 and now are used in optical fiber communications.) Creating the soliton requires that one of the sandwich layers be magnetized perpendicular to the plane of the sandwiched layers; then an electric current is forced through a small channel in the sandwich. Once the soliton is established, the magnetic orientation oscillates at more than a billion times a second.
"That's the frequency of microwaves," says NIST physicist Thomas Silva. "You might use this effect to create an oscillator in cell phones that would use less energy than those in use today. And the military could use them in secure communications as well. In theory, you could change the frequency of these devices quite rapidly, making the signals very hard for enemies to intercept or jam."
Silva adds that the oscillator is predicted to be very stable—its frequency remaining constant even with variations in current—a distinct practical advantage, as it would reduce unwanted noise in the system. It also appears to create an output signal that would be both steady and strong.
The team's prediction also has value for fundamental research.
"All we've done at this point is the mathematics, but the equations predict these effects will occur in devices that we think we can realize," Silva says, pointing out that the research was inspired by materials that already exist. "We'd like to start looking for experimental evidence that these localized excitations occur, not least because solitons in other materials are hard to generate. If they occur in these devices as our predictions indicate, we might have found a relatively easy way to explore their properties."
This animation shows the development of the soliton over the course of about 2.7 nanoseconds. Current begins passing through the channel in the center, causing the magnetization to oscillate. These oscillations initially move throughout the layer, but after 1.8 ns the magnetization under the hole inverts to form the soliton (center changes to red) and the oscillations are then localized.
(Photo Credit: NIST)
The animation this frame was taken from (q.v.) shows the development of the soliton over the course of about 2.7 nanoseconds. Current begins passing through the channel in the center, causing the magnetization to oscillate. These oscillations initially move throughout the layer, but after 1.8 ns the magnetization under the hole inverts to form the soliton (center changes to red) and the oscillations are then localized.
(Photo Credit: NIST)
Source: National Institute of Standards and Technology (NIST)