High-temperature Superconductor Spills Secret: A New Phase of Matter

March 24, 2011 - High-temperature Superconductor Spills Secret: A New Phase of Matter

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Menlo Park, Calif. — Scientists have found the strongest evidence yet that a puzzling gap in the electronic structures of some high-temperature superconductors could indicate a new phase of matter. Understanding this “pseudogap” has been a 20-year quest for researchers who are trying to control and improve these breakthrough materials, with the ultimate goal of finding superconductors that operate at room temperature.

"Our findings point to management and control of this other phase as the correct path toward optimizing these novel superconductors for energy applications, as well as searching for new superconductors," said Zhi-Xun Shen of the Stanford Institute for Materials and Energy Science (SIMES), a joint institute of the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University. Shen led the team of researchers that made the discovery; their findings appear in the March 25 issue of Science.

Superconductors are materials that conduct electricity with 100 percent efficiency, losing nothing to resistance. Currently used in medical imaging, highly efficient electrical generators and maglev trains, they have the potential to become a truly transformative technology; energy applications would be just one beneficiary. This promise is hampered by one thing, though: they work only at extremely low temperatures. Although research over the past 25 years has developed “high-temperature superconductors” that work at warmer temperatures, even the warmest of them—the cuprates—must be chilled half-way to absolute zero before they will superconduct.

The prospect of being able to dramatically increase that working temperature, thus making superconductors easier and cheaper to use, has kept interest in the cuprates at the boiling point. But to change something you have to understand it, and a puzzle called the pseudogap has stood in the way.

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