Thin crystalline sheets that shift the positions of their ions in response to an electric field look more promising as a fast, low power memory devices in personal and handheld computers, following new research in the US.

Work by Brian Stephenson and colleagues, at Argonne National Laboratory in Illinois, suggests there is no fundamental limit to the thickness of crystals that can exhibit this property, known as the ferro-electric effect. Previously scientists had found that films thinner than four nanometres ceased to exhibit ferro-electricity.

The phenomenon is currently exploited in so-called “Fe-RAM” devices, but these applications are limited to those needing only a low memory density, such as smart cards. For example, a commercial Fe-RAM chip made by Ramtron in Colorado Springs, Colorado, is 10 by 10 millimetres in area but holds just 256 kilobits of data.

But the new discovery could allow the amount of data stored on a chip of that size to be increased by at least a factor of 100, says Stephenson. Such miniaturisation would open up the possibility of personal computers and handheld devices based on Fe-RAM. These would be lower power than existing RAM devices, because the data is not lost when the power is switched off. They would also be faster than the FLASH memory used in digital cameras and memory sticks.

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