HOUSTON -- (May 28, 2010) -- A team of U.S. and Chinese physicists are zeroing in on critical effects at the heart of the latest high-temperature superconductors -- but they're using other materials to do it.
In new research appearing online today in the journal Physical Review Letters, the Rice University-led team offers new evidence about the quantum features of the latest class of high-temperature superconductors, a family of iron-based compounds called "pnictides" (pronounced: NICK-tides).
"In correlated electron systems like the pnictides and their parent compounds, the electrons are caught in a competition between forces," said Rice physicist Qimiao Si, a co-author of the study. "On the one hand, they are compelled to move around, and on the other, they are forced to arrange themselves in a particular way because of their desire to repel one another. In this study, we varied the ratio between these competing forces in an effort to find the tipping point where one takes over from the other."
The aim of the research is to better understand the processes that lead to high-temperature superconductivity. If better understood and developed, high-temperature superconductors could revolutionize electric generators, MRI scanners, high-speed trains and other devices. In today's wiring, electricity is lost due to resistance and heating. This happens because electrons bump and ricochet from atom to atom as they pass down wires, and they lose a bit of energy in the form of heat each time they bounce around.
Almost a century ago, physicists discovered materials that could conduct electrons without losing energy to resistance. These "superconductors" had to be very cold, and it took physicists nearly 50 years to come up with an explanation for them: The electron-electron repulsion in these low-temperature superconductors was so weak that with the mediation of lattice vibrations, electrons overcame it, paired up and glided freel
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