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[R]esearchers at the National Laboratory for Intense Magnetic Fields (LNCMI) in Toulouse, France, uncovered a key property of the crystal, a matte-black ceramic in a class of materials called cuprates that are the most potent superconductors known. The findings, reported today in the journal Nature, provide a major clue about the inner workings of cuprates, and may help scientists understand how these materials allow electricity to flow freely at relatively high temperatures.
[Researchers] used their 90-tesla magnet — which creates a magnetic field nearly two million times as strong as the one enshrouding Earth — to momentarily strip away superconductivity in their cuprate sample. This revealed details of the underlying phase from which the behavior seems to arise.
With the veil lifted, the scientists discovered a sharp change in behavior at what appears to be a “quantum critical point” in cuprates, reminiscent of the freezing point of water. Theorists have long speculated that such a quantum critical point might exist, and that it could play a key role in superconductivity, said Andrey Chubukov, a condensed-matter theorist at the University of Minnesota. “One thing is to say this; another thing is to measure it,” Chubukov said.
[C]uprates superconduct at much higher temperatures than other materials, suggesting that their electrons are paired by a different and stronger glue. But cuprates must still be cooled below minus 100 degrees Celsius before they become superconductive. The glue must be further strengthened if superconductors’ operating temperatures are to be dialed up. For 30 years scientists have asked: What is the glue — or, more precisely, the quantum mechanical interaction between electrons — that causes superconductivity to arise in cuprates?
While the detection of a quantum critical point does not definitively answer that question... [their finding] knocks several proposals for the electron-pairing glue in cuprates out of the running.
Normally, this “carrier density” increases gradually as a function of doping. But at a critical point, it would be expected to change suddenly, indicating a spontaneous reorganization of the electrons in the crystal. And that’s what the scientists measured: a sharp, sixfold jump in the carrier density at 19 percent doping, the expected location of the critical point.
originally posted by: imbalanced
so i guess that answers my question, it wasnt clear for me in the artcle if they needed to super cool the wires, i guess the do using liguid nitrogen. It would be cool if they could make superconducting wires that run at room temprature. I am thinking some kinda copper that is alligned like it says in the article. Maybe a copper crystal or something ? Im guessing its all in the manufacture process, when making copper its heated and all of the atoms get jarred and disoriented imposeing resistance. Does anyone think making copper with a process that would align the atoms in a more uniform direction would make any diffrence ?
The prediction was that "Cooper pairs" of electrons in a superconductor could exist in two possible states. They could form a "superfluid" where all the particles are in the same quantum state and all move as a single entity, carrying current with zero resistance—what we usually call a superconductor. Or the Cooper pairs could periodically vary in density across space, a so-called "Cooper pair density wave." For decades, this novel state has been elusive, possibly because no instrument capable of observing it existed.
[They] studied a cuprate incorporating bismuth, strontium, and calcium (Bi2Sr2CaCu2O8) using an incredibly sensitive STM that scans a surface with sub-nanometer resolution
[The scanning technique] reveals the density of Cooper pairs at any point, and it showed periodic variations across the sample, with a wavelength of four crystal unit cells. The team had found a Cooper pair density wave state in a high-temperature superconductor, confirming the 50-year-old prediction.
The most synergistic combination of elements found to facilitate high-temperature superconductivity are tin, tellurium, barium, and manganese in a copper-oxide matrix... Since Tc has previously been found to correlate directly with planar weight ratio (PWR), three new compounds with these same elements were synthesized using progressively higher planar weight ratios in each. The results reveal that superconductivity is still possible at temperatures as high as 187 Celsius (460K/368F), giving new meaning to the term "warm superconductor."