Most of the world's 2.7Zbyte of data is held on hard disk drives, with the data read by sensors that scan over the disk's surface as it spins. But because this involves moving parts, there are limits on how fast it can operate.
For computers to run faster, ‘solid-state’ drives have been created that eliminate the need for moving parts - essentially making the data move, 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 faster than normal hard disks, they last less time before becoming unreliable, are more expensive and run 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 down which magnetic ‘bits’ of data run. 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 will limit battery life, increase energy bills and CO2 emissions.
Dr Tom Hayward from the University of Sheffield and Professor John Cunningham from the University of Leeds have devised a 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. Although already 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.
Dr Hayward said: "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. Because of this, we think a single sound wave could be used across 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."
