Researchers from the University of Leeds and Sheffield University have figured out a way to transport data through magnetic nanowires by using acoustic waves for force. It is estimated that this technology for the racetrack solid-state memory, would greatly benefit by this new technique with increased speeds and reduced power consumption.

Racetrack memory uses the transition between different magnetic moments (directions) in the domain walls separating each of the magnetic areas found in the nanowires that make up the memory. Developed by IBM, this works using a system of binary data and each transition between these areas results in an angular displacement (a change of magnetic “direction”) of 90 or 180 degrees.

The usual troubles faced while moving data across the lines is posed by the magnetic inertia in the domain walls. The trick to transporting this data which is 20 times smaller the size of a human hair, is to overcome the inertia with strong magnetic fields and induced electric currents. However, this consumes a lot a more power than gives speed.

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In the sound wave method, two counter-propagating surface acoustic waves (SAW) are passed across the piezoelectric substrate to which the nanowires are fixed. When the two waves meet, a standing wave is created which then can manipulate and rearrange the arrays for effective circulation of energy across the wires. Technically, the domain walls become attracted to and pinned at the points of antinodes of standing stress/strain waves and the data moves along the wires in a ratcheted motion toward positions of minimum stress. Thus, by shifting the frequency of the SAWs, multiple domain walls can be synchronously propagated at high velocities. Basically, changing the pitch would change the direction.

“The key advantage of surface acoustic waves in this application is their ability to travel up to several centimeters without decaying, which at the nano-scale is a huge distance,” said Doctor Hayward. “Because of this, we think a single sound wave could be used to ‘sing’ to large numbers of nanowires simultaneously, enabling us to move a lot of data using very little power. We’re now aiming to create prototype devices in which this concept can be fully tested.”

Author: Technology Blog