Link between electron pair density and the temperature limit of superconductivity

Discussion in 'Physics & Math' started by Plazma Inferno!, Sep 1, 2016.

  1. Plazma Inferno! Ding Ding Ding Ding Administrator

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    Back in the 1980s, scientists had discovered that some copper containing materials called cuprates had zero electrical resistance at record breaking temperatures. These materials are now known as high temperature superconductors due to their ability to retain superconductivity at temperatures above the still frigid boiling point of liquid nitrogen (minus 321 degrees F) -- previously thought to be impossible.
    When a material is in its superconducting state, it also has the ability to expel external magnetic fields. It can also generate super intense magnetic fields due to the ability to sustain large electric currents without overheating.
    Today you can find superconductors at work inside MRI and NMR machines in hospitals as well as the tunnels of the Large Hadron Collider near Geneva, Switzerland. However, for these superconductors to work, we still need to keep them cool with liquid nitrogen -- gallons upon gallons of it. If we decided to try to harness their power on a larger scale, such as for an international power grid or an affordable mag-lev train system, the cooling cost will go through the roof. So ultimately we need something that can superconduct at "real-world" temperatures.
    Even after spending decades trying to unravel the mystery behind high temperature superconductivity, scientists still don't quite understand why superconductivity occurs in certain materials and why it stops at a certain temperature.
    Thanks to the recent research, we might have finally caught a glimpse of light. Researchers at Brookhaven describe the electron pairs as couples on a dance floor. When the floor gets too hot, the couples start to break up. Researchers discovered that when more of these "couples" are crammed onto the dance floor, they tend to stay together up to higher temperatures.

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    Inside a superconductor, electrons (-) that normally repel each other can pair up through a middleman - protons (+)

    The obvious next step is to test the findings on other cuprates and perhaps even other superconductors.
    Another route is to explore methods to manipulate the electron pairs' density, now that scientists know its relationship to the temperature limit. Either way, it seems likely that this discovery will breathe new life into the hunt for the holy grail that is room temperature superconductivity.

    https://www.insidescience.org/news/superconducting-dance-electron-pairs

    Paper: http://www.nature.com/nature/journal/v536/n7616/full/nature19061.html
     
    danshawen likes this.
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  3. danshawen Valued Senior Member

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    I'm not sure this helps the situation very much because superconducting materials also have a critical magnetic field density above which the superconductivity breaks down. This was the prime motivation for forming such materials into flat ribbons which can be seen for example in he construction of the steering dipole and focusing quadrupole magnets of the LHC.

    How one would be able to optimize both parameters (current and pair density) at once would pose a problem because the more pairs you have, the more careful you must move them to be certain you do not exceed the critical current density.

    Plasma inferno's other very bright post about electron behavior with nanowire technology might offer a solution.
     
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  5. danshawen Valued Senior Member

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    Got a partial solution. A superconductor shaped like a corrugated ribbon. The magnetic flux from adjacent current paths can't add together in a way that exceeds the critical magnetic field. Not patented yet. Here's your chance.
     
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