Squeezable Ferroelectrics May Create Instant-On Memory
Editor's Note: We should all thank Edison for his phonograph, the very first real-time data recorder. One could argue that without the development of stored music, we may have never made the leap to storing other information electronically.
(Cornell Chronicle Online ) - The technology of storing electronic information -- from old cassette tapes to shiny laptop computers -- has been a major force in the electronics industry for decades.
Low-power, high-efficiency electronic memory could be the long-term result of collaborative research led by Cornell materials scientist Darrell Schlom. The research, to be published April 17 in the journal Science (Vol. 324 No. 5925), involves taking a well-known oxide, strontium titanate, and depositing it on silicon in such a way that the silicon squeezes it into a special state called ferroelectric -- a result that could prove key to next-generation memory devices.
Ordinarily, strontium titanate in its relaxed state is not ferroelectric at any temperature. The researchers have demonstrated, however, that extremely thin films of the oxide -- just a few atoms thick -- become ferroelectric when squeezed atom by atom to match the spacing between the atoms of underlying silicon.
"Changing the spacing between atoms by about 1.7 percent drastically alters the properties of strontium titanate and turns it into a material with useful memory properties," said Long-Qing Chen, professor of materials science and engineering at Pennsylvania State University, a member of the research team whose calculations predicted the observed behavior five years ago.
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(IMAGE) - The arrangement between atoms of a film of strontium titanate and the single crystal of silicon on which it was made is shown on the left. When sufficiently thin, the strontium titanate can be strained to match the atom spacing of the underlying silicon, and it becomes ferroelectric. On the right this schematic has been written into such a film, utilizing the ability of a ferroelectric to store data in the form of a re-orientable electric polarization.
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