'Electron pairing' found well above superconductor's critical temperature

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Physicists have found "electron pairing," a hallmark feature of superconductivity, at temperatures and energies well above the critical threshold where superconductivity happens.

Rice University's Doug Natelson, co-corresponding author of a paper on the work in this week's NatureCooperative of the electrons, the discovery of Cooper peers of the electrons "The thing that is more than a few people. where the peers form, and there 's a lower energy scale where they all decide to join hands and act collectively and coherently, the behavior that' s one about superconductivity.

Electrical resistance is so common in the modern world that it is most likely to be used for computers, smartphones and electrical appliances. This heating happens because electricity does not flow freely through the metal wires and silicon chips inside the devices. Instead, flowing electrons occasionally bump into atoms or one another, and each collision produces a tiny bit of heat.

Physicists have known that they can not be called superconductors. And in 1957, they figured out why: Under specific conditions, including typically very cold temperatures, electrons join together in something-that's normally forbidden to their mutual repulsion-and as peers, they can for free.

"To get superconductivity, the general feeling is that you need peers, and you need to achieve some coherence among them," said Natelson, who partnered with the Rice Experts at the Brookhaven National Laboratory and the University of Connecticut. "The question, for a long time, was, 'When do you get peers?' Due to the fact that we are trained as peers, coherence and superconductivity would follow. "

Electron peers are named for Leon Cooper, the physicist who first described them. In addition to explaining classical superconductivity, physicists believe that cooperatives bring about high-temperature superconductivity, an unconventional variant discovered in the 1980s. It was dubbed "high-temperature" because it occurs at temperatures that are still very cold, are considerably higher than those of classical superconductors. Physicists have long dreamed of making high-temperature superconductors that work at room temperature, a development that would be radically changed the way energy is made, moved and used worldwide.

<div data-thumb = "https://scx1.b-cdn.net/csz/news/tmb/2019/ahallmarkofs.jpg" data-src = "https://scx2.b-cdn.net/gfx/ news / hires / 2019 / ahallmarkofs.jpg "data-sub-html =" Rice University Physicists (from left) Liyang Chen, Panpan Zhou and Doug Natelson and colleagues at Brookhaven National Laboratory and the University of Connecticut found evidence of electron pairing – a hallmark feature of superconductivity – at temperatures and energies well above the critical threshold where superconductivity occurs. Nature. Credit: Jeff Fitlow / Rice University ">

<img src = "https://scx1.b-cdn.net/csz/news/800/2019/ahallmarkofs.jpg" alt = "A hallmark of superconductivity, beyond superconductivity itself” title=”Rice University physicists (from left) Liyang Chen, Panpan Zhou and Doug Natelson and colleagues at Brookhaven National Laboratory and the University of Connecticut found evidence of electron pairing – a hallmark feature of superconductivity – at temperatures and energies well above the critical threshold superconductivity occurs. The research appears this week in Nature. Credit: Jeff Fitlow / Rice University”/>

But while physicists have a clear understanding of how and why electron pairings occur in classical superconductors, the same can not be said of high-temperature superconductors like the lanthanum strontium copper oxide (LSCO) featured in the new study.

Every superconductor has a critical temperature at which electrical resistance disappears. Natelson said theories and studies of copper-oxide superconductors over the past 20 years have suggested that cooperators form this critical temperature and become more critical.

"If that's true, and you've already got peers at higher temperatures, the question is, 'Can you also get coherence at these temperatures?'" Natelson said. "Can you somehow convince them to start their dance in the region known to the pseudogap, to phase space at higher temperatures and energy scales than to the superconducting phase."

In the Nature Ultrasound in the field of ultrapure conduction noise in ultraviolet light LCSO samples grown in the lab of Brookhaven's Ivan Božović, co-corresponding author of the study.

"The best material in the world, and our measurements and conclusions were only possible because of the purity of those samples," Natelson said. "He and his team made devices called tunnel junctions, and instead of looking at the electrical current, we looked at fluctuations in the current called noise shot.

"In most cases, if you measure current, you're measuring an average and ignoring the fact that current charges in chunks of charge," Natelson said. "It's something like the difference between measuring the average daily rainfall and measuring it."

By measuring the variation in the volume of electrical charges flowing through LCSO junctions, the study of the effects of superconductivity .

"Some of the load must be coming in larger chunks, which are the peers," he said. "That's unusual, because it's a superconductor, and you get a great deal of experience with it, the peers get ripped apart, and you only see single charges.

"It looks like LCSO contains another energy scale where the peer group is not yet acting collectively," Natelson said. "People have previously offered the subject of this sort of thing, but this is the first direct evidence for it."

Natelson said it is too early to say that it is possible to use it in a new way. But Božović said the discovery has "deep implications" for physicists who study high-temperature superconductors and other types of condensed matter.

"In some sense, the textbook chapters have been rewritten," Božović said. "From this study, it appears that we have a new type of metal, in which a significant fraction of the current is conducted by the electron pair. example, using the same technique to test other cuprates or superconductors, insulators and layer thicknesses. "