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Surface acoustic waves improve 'racetrack memory' performance

03 November 2015

Two British engineers are exploring the use of surface acoustic waves to speed the transfer of data through magnetic solid-state drives: so-called 'racetrack memories'.

Image: Shutterstock

The world's 2.7 zettabytes (that's 2.7 followed by 21 zeros) of data are mostly held on hard disk drives, but because this involves moving parts, there are limits on how fast data can be transferred in and out of these devices. For computers to run faster, 'solid-state' drives are preferred as they eliminate the need for moving parts - essentially making the data move, and not the device on which it's stored.

Flash-based solid-state disk drives have achieved this, and store information electrically rather than magnetically. However, while they operate much faster than normal hard disks, they last much less time before becoming unreliable, are much more expensive and still run much slower than other parts of a modern computer - limiting total speed.

Creating a magnetic solid-state drive could overcome all of these problems. One solution being developed is 'racetrack memory', which uses tiny magnetic wires, each one hundreds of times thinner than a human hair, down which magnetic 'bits' of data run like racing cars around a track. Existing research into racetrack memory has focused on using magnetic fields or electric currents to move the data bits down the wires. However, both these options create heat and reduce power efficiency, which limits battery life and increases energy bills and CO2 emissions.

Dr Tom Hayward from the University of Sheffield and Professor John Cunningham from the University of Leeds have together come up with a completely new solution: passing sound waves across the surface on which the wires are fixed. They also found that the direction of data flow depends on the pitch of the sound generated.

The sound used is in the form of surface acoustic waves, and while these has already been harnessed for use in electronics and other areas of engineering, this is the first time surface acoustic waves have been applied to a data storage system.

"The key advantage of surface acoustic waves in this application is their ability to travel up to several centimetres without decaying, which at the nano-scale is a huge distance," says Dr Hayward, from Sheffield's Faculty of Engineering. "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."


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