Where's the glue?

Scientists find a surprise when they look for what binds in superconductivity

For more than 20 years since the discovery of high-temperature superconductivity, scientists have been debating the underlying physical mechanism for this exotic phenomenon, which has the potential to revolutionize the electrical power distribution network.

They've argued at length over the origin of what some have imagined to be a microscopic "glue" that binds the electrons into pairs so they glide effortlessly, overcoming their normal repulsion in typical metals. Is it magnetism or vibrations in the lattice structure of the material or something else"

Now, provocative results yielded by two years of experiments carried out at Princeton University have a group of scientists saying that high-temperature superconductivity does not hinge on a magical glue binding electrons together. The secret to superconductivity, they say, may rest instead on the ability of electrons to take advantage of their natural repulsion in a complex situation.

Reporting in the April 11 issue of the journal Science, the team has uncovered an unexpected connection between the behavior of electrons when they pair up -- a key requirement for superconductivity -- and when the electrons are repelling one another at temperatures far above the critical temperature at which a material superconducts. Their experiments have shown that electrons exhibit a characteristic behavior when repelling each other that, strangely enough, signals their special talent for pairing and flowing without resistance when these complex materials are cooled to low temperatures.


Source: http://www.eurekalert.org/pub_releases/2008-04/pu-wtg040708.php