Good physics theorists believe in miracles when it comes to superconductivity
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A Final Answer on How High-Temperature Superconductors Don’t Work?
by Adrian Cho on 29 March 2012, 7:10 PM | 2 Comments
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Plane as day. A schematic drawing of a copper-and-oxygen plane in a high-temperature superconductor and a Cooper pair of electrons. The red squiggle signifies incoming laser light.
Credit: Image courtesy of Claudio Giannetti
For decades, physicists have debated the origins of high-temperature superconductivity—the ability of some materials to carry electricity without resistance at temperatures up to 138 kelvin. Now, new data nix one possible explanation, albeit a less popular one, a team claims. If the finding holds up, it would sever any connection between ordinary superconductors, such as lead and niobium, and the high-temperature materials.
Tiny vibrations called phonons—the essential ingredient in the mechanism behind ordinary superconductors-play no significant role in high-temperature superconductivity, the team claims. “Hopefully, the paper will put an end to this story,” says Andrey Chubukov, a theorist at the University of Wisconsin, Madison, who was not involved in the work. Advocates of phonon-based theories of high-temperature superconductivity say they are not persuaded, however.
In an ordinary metal, current meets with resistance as the electrons in it deflect off the vibrating ions in the metal’s “crystal lattice.” But in a superconductor cooled below its “critical temperature,” the electrons form loose “Cooper pairs.” Deflecting an electron then requires breaking a pair. At low temperatures, there isn’t enough energy around to do that, so the pairs glide through unimpeded. As a result, electric current flows freely through the material—like a milkshake miraculously zipping through a straw with no one sucking on it.
