Our need to store data is growing at an astonishing rate. An estimated 2.7 zettabytes (2.721) of data are currently held worldwide, equivalent to several trillion bytes for every one of the 7 billion people on Earth. Accessing this data quickly and reliably is essential for us to do useful things with it – the problem is, all our current methods of doing so are far too slow.
Conventional hard-disk drives encode data magnetically on spinning discs, from which the data is read by a sensor that scans over its surface as it rapidly rotates. Their moving parts introduce the potential for mechanical failures, and limits the speeds possible. This slows everything down.
Much faster are solid-state storage devices, which have no mechanical parts and store data as tiny electrical charges. Most modern laptops, all modern smartphones and digital cameras, and many other devices use this technology – also known as flash memory. 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.
A solid-state drive that encodes data magnetically would be ideal. IBM is developing one variation, known as racetrack memory. This uses collections of tiny nanowires hundreds of times thinner than a human hair. Data is magnetically encoded as strings of ones and zeros along the nanowire, but although it can move data through it far faster than typical hard disks, a key challenge is to find ways to make the data "flow" through the nanowires in order to pass it across the sensors that read and write data to the wire. This can be achieved by applying magnetic fields or electric currents, but this generates heat and reduces power efficiency, affecting battery life.
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