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Hydrocarbon Superconductor Discovered
Picene becomes a superconductor below 18 kelvin
3 March 2010—In a development that if independently confirmed could lead to an entirely new class of superconductors, a group of Japanese scientists—led by Professor Yoshihiro Kubozono of Okayama University—is reporting that a simple hydrocarbon, picene, exhibits superconductivity below 18 kelvin, a relatively high temperature. The Japanese team details its findings in this week’s issue of Nature .
Superconductivity is a phenomenon whereby the resistance of a material to the flow of electricity vanishes. If confirmed, this will be the first time in a decade that a new organic, high-temperature superconductor has been discovered.
”The results look quite interesting, and I would expect [them] to cause a stir in the superconductivity community,” says Jeff Lynn, a physicist at the National Institute of Standards and Technology (NIST), in Gaithersburg, Md., who investigates superconductivity.
Kubozono and colleagues have found that picene becomes a superconductor when it is laced with potassium or rubidium and then chilled. Picene is an organic compound found in crude oil; it is made up of 22 carbon atoms and 14 hydrogen atoms. It looks like five benzene rings—common organic molecules—fused together in a staggered line.
”Most people…wouldn’t think of hydrocarbons as being electrically interesting,” says the University of Liverpool’s Matthew Rosseinsky and Durham University’s Kosmas Prassides, who coauthored a commentary in Nature explaining the significance of the work. ”This is exciting news for superconductivity researchers and should stimulate extensive work on the electronic properties of other acenes [the family of aromatic compounds to which picene belongs].”
The Japanese team doped the molecules with potassium or rubidium in a process called intercalation, in which the metal atoms are inserted between parts of the picene molecule. They created a thin film of the intercalated picene and built a field-effect transistor to test for superconductivity.