The findings, which appear in the March 4 issue of the journal Nature, identify three factors that explain a perplexing pattern in the temperatures at which multi-layered ceramic materials become superconductors. The study could advance research in medical imaging, electrical power transmission and magnetically levitating trains. Its authors are U of T physics professor Hae-Young Kee and post-doctoral fellow Klaus Vlker, and Professor Sudip Chakravarty of UCLA's physics and astronomy department.

Superconductivity is a phenomenon that occurs when certain metals are cooled to near absolute zero, a temperature equivalent to zero degrees Kelvin (K), -273 C or -459 F. In ceramic materials, the phenomenon appears at about 100K. At a so-called critical temperature--that varies depending on the number of layers within the ceramic substance--the material becomes capable of conducting electricity without any energy loss.

Despite the value of such an efficient system, the supercooling--usually done with liquid nitrogen or liquid helium--makes superconductors impractical for many applications. "A room temperature superconductor would be a revolution, but even a superconductor with a higher critical temperature would have extremely important implications for multiple industries," says Kee, who holds the Canada Research Chair in Theoretical Condensed Matter Physics.

Materials scientists have developed a group of "high-temperature" superconductors made with layers of copper oxides sandwiched between insulating filler material. This material reaches critical temperatures in the range of roughly 130K--the highest know critical temperatur
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Contact: Nicolle Wahl
nicolle.wahl@utoronto.ca
416-978-6974
University of Toronto
3-Mar-2004