Sound to power hard drives of Future!

Data Storage estimates taken on worldwide note say that over 2.7 Zettabytes of data is currently being held on a global note, which is equivalent to several trillion bytes for every one of the 7 billion people on earth. So, accessing the data quickly and reliably is essential for us to do useful things with it. But the problem is that the current methods of doing so are far too slow.

Hard-disk drives encode data magnetically on spinning platters, from which the data is read by a disk head that scans over its surface as it rapidly rotates. Though, things are working well till date, the presence of moving parts introduces the potential for mechanical failures, and limits the speeds possible. This slows everything down.

Solid-state storage devices on the other hand have no mechanical parts and store data as tiny electrical charges. However, while solid-state devices are much faster they have a much shorter lifespan than hard disks before becoming unreliable, and are much more expensive. And despite their speed, they’re still far slower than the speed at which data travels between other components of a computer, and so still act as a brake on the system as a whole.

To counter this problem, IBM is coming up with “racetrack memory”. In this concept, tiny nanowires, which are 100 times thinner than human hair, are taken and data is magnetically encoded as strings of 1’s and 0’s along the Nanowire. Although, the data movement between the nanowires and the R/W sensors is fast, the challenge will be to make the data move across the nanowires. This can be achieved by applying magnetic fields or electric currents, but this generates heat and reduces power efficiency, affecting battery life.

Researchers at University of Sheffield in conjunction with John Cunningham at the University of Leeds have been using simulations to explore ways of making racetrack memory more efficient and stumbled upon a surprising solution using sound waves.

In our simulations we created vibration-sensitive magnetic nanowires on top of layers of piezoelectric materials, which stretch when we apply an electric voltage. By applying a rapidly-switching voltage they begin to vibrate, creating a special sort of sound wave known as surface acoustic waves.

Scientists at University of Sheffield have created two sound waves, one flowing along the nanowires and one flowing backwards. These waves combine together to create regularly spaced regions of the nanowire which vibrate strongly separated by regions that don’t vibrate at all. At this juncture, it is observed that the magnetic data bits are attracted to and held in place at the strongly vibrating sections.

When a change in the pitch of two sound waves is made one “sings” a higher note and one on a lower note. This will make the vibrating regions start flowing along the nanowire, pulling the data bits with them just as is required for racetrack memory. If we switch the notes around, the data flows in the opposite direction. By using only sound alone it’s possible to move data in both directions.

At the moment simulations show data flowing at around 100mph (160kph). This sounds pretty fast, but the scientists want it to be ten times faster. However the really exciting implications of this stem from the unique properties of surface acoustic waves. Because they only exist right at a material’s surface they lose energy very slowly, and can travel as much as several centimeters (which is huge when you consider the tiny size of the nanowires).

As the nanowires are so small a single pair of waves could be applied to a very large number of wires, and therefore to the data within them on a simultaneous note.

Potentially this creates a very power efficient way of moving lots of data around quickly.

A lot of development is needed on this note and IBM’s research will only succeed when a prototype of this experiment yields encouraging results.

And only time will suggest, whether this experimental concept will apply only to hard disk drives or solid state drives.

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