Atoms never forget

Mark Peplow, Arrays of atoms could make faster, cheaper memory devices.

Memory chips that store data by using electrical pulses to rearrange atoms could revolutionize the next generation of mobile phones and digital cameras. So say researchers who have built a device that proves the idea can deliver faster, cheaper memory.

Computers use a binary code to store their information in capacitors that can hold electrons in two distinct states, like a switch that can be either 'on' or 'off'. But since electrons can leak out, each capacitor must be recharged thousands of times every second. And if the power supply dies, so does all your data.

Now Martijn Lankhorst and his colleagues at Philips Research Laboratories in Eindhoven, the Netherlands, have shown that instead of using electrons, it's possible to create two states using an ordered or disordered arrangement of atoms.

They use a material called antimony telluride, which starts off in an 'amorphous' state, with all its atoms jumbled up. But a small pulse of electricity provides enough heat to make the atoms line up into rows, creating an ordered, crystalline arrangement.

A second, higher-voltage pulse melts the crystalline structure, resetting the material back to its jumbled state. A computer could tell the difference between the two because the crystalline phase has a much lower electrical resistance.

Wiring lots of tiny pieces of antimony telluride together would create a memory chip that could store information in a stable way, without having to be continually charged up.

Imagine you could start your laptop and have it ready for you to work in less than a second.

Matthias Wuttig
RWTH Aachen University, Germany

The approach has huge potential, says Matthias Wuttig, a materials scientist at the RWTH Aachen University in Germany. "Imagine you could start your laptop and have it ready for you to work in less than a second," he says, "or that you were able to record and watch full-length movies on your mobile phone."

The idea isn't new - Stanford Ovshinsky first proposed the concept for such 'Ovonic' devices in 19681. But it has taken researchers until now to find a material that can reliably change states millions of times without degrading, and to develop the techniques needed to wire such tiny components together.

The research is published online in Nature Materials2

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