By Malcolm Ritter
Associated Press
In a startling result, scientists have found that a common metal compound can carry electricity with virtually no resistance at a higher temperature than previously thought possible. The compound might become useful for building superfast computers.
Two labs report that the magnesium-boron compound becomes "superconducting'' at temperatures of around minus 388 degrees to minus 389 degrees. That is still mighty cold, but it is warmer than the previous record for simple metallic compounds of about minus 418.
Since superconducting compounds must be chilled to work, scientists are eager to find materials that work at higher, more easily attained temperatures.
The new work will be reported in next Thursday's issue of the journal Nature by Jun Akimitsu of the Aoyama-Gakuin University in Tokyo with colleagues, and in next Monday's issue of Physical Review Letters by Paul Canfield and colleagues at the Ames Laboratory and the department of physics and astronomy at Iowa State University. Canfield's group followed up on Akimitsu's work.
The Japanese work was startling because the superconductivity temperature was so much higher than ever observed in such metallic compounds, Robert Cava of Princeton University wrote in a Nature commentary.
"The field of superconductivity has been rocked'' by the news, he said.
Cava said superconductivity researchers have virtually ignored such simple metallic compounds for 15 years in favor of a class of oxygen-containing materials, which superconduct at much higher temperatures than even the newly reported compound, up to minus 172 degrees.
Some experts said the magnesium-boron compound might pay off in making very fast computer components, where the oxygen-containing materials have proven hard to work with.
John Rowell, a professor in materials science at Northwestern University, said scientists have done much work with lower-temperature materials like the metallic element niobium. If the magnesium-boron material could be used instead, the components might work as much as four times faster because of the higher superconducting temperature, he said.
He noted that it is not clear whether the overall idea of superconducting electronics will prove useful in computers.
Ted Geballe, a superconductivity expert at Stanford University, said he gives the magnesium-boron material an outside chance of becoming useful in electronics, but he added that "it's so new it's worth looking at.''
Cava, in his commentary, said superconducting materials based on the compound might one day be able to carry more current than wires made from the oxygen-bearing materials. Scientists hope superconducting wire will be able to routinely carry electricity without substantial losses to resistance.
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