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High Temp. Superconductivity

  1. Jan 28, 2012 #1
    So how does High Temperature Superconductivity work? Classical Superconducitivty is done by cooper pair and the BCS mechanism, what is the counterpart in High Temp SC? Can it reach room temperature?
     
  2. jcsd
  3. Jan 30, 2012 #2
    Whoever answers that will have a Nobel prize rather quickly...at least that is what my profs tell me :)
     
  4. Jan 31, 2012 #3
    nobody knows the answer~ that's why people are crazy for various condensed matter problems so as to shed light to the problems.
     
  5. Feb 1, 2012 #4

    DrDu

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  6. Feb 1, 2012 #5

    cgk

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    Thanks for that link. That's interesting.

    That being said, I think using the term "understood" in this context is a bit much. While there may be (plenty of..) models of which one could expect that they explain the HTSC behaviors, and theoretical approaches to treating them, in practice the relevant many body physics can still be not solved to a satisfactory degree numerically.

    Even in the year 2012 there are still papers coming out dealing with the ground state of the two-dimensional Hubbard model on square lattices, because even for this system, which is the simplest imaginable model system for this kind of strongly correlated electronic structure problem, even the qualitative behavior is not known exactly. And that is not even taking into account that the Hubbard model is at best a very bad caricature of a real system[1], and treating a proper cuprate from first principles is orders of magnitude more complicated. As long as a consensus is not even reached for such simple systems, claiming that much more complicated systems are basically explained is probably a bit optimistic.

    [1] (it is not even clear if it is even relevant for high temperature superconductivity, and if it is, then for which kinds)...
     
  7. Feb 1, 2012 #6

    DrDu

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    Well, I am referring to the Cuprates.
    Up to now, I have not tried to understand HTSC as I didn't even understand low temperature SC.
    Now I am feeling more confident and I thought Anderson might be a good starting point.
    There are few people with a better overview over the matter as he already in young years clarified the problems of gauge invariance in the BCS model.
    Of course a plethora of other models besides his "plain vanilla" RVB model have been proposed. But which ones are still seen as likely candidates today by a larger group of persons?
    After more than 20 years there has to be some consensus at least on the basic facts and much must have been ruled out by experiment.
     
  8. Feb 2, 2012 #7
    I came across this today. This work supposedly "reduced the number of theories for HTC from dozens to few"

    http://www.physique.usherbrooke.ca/taillefer/publication/Nature-463-519.pdf [Broken]
     
    Last edited by a moderator: May 5, 2017
  9. Feb 3, 2012 #8

    f95toli

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    Not really, I am not currently working with HTS but I still listen to plenaries at conferences etc.
    and AFAIK there there is nothing even approaching a consensus. Most people still thinks that we need more experimental data before we can even start working on a "proper" theory.
    Also, although it has been more than 20 years I'd say we've only had access to "clean" samples for the last 5-10 years (even for bulk); and people are still working on improving film growth and so on. All this effort has meant that we now have access to things like infinite layers and similar structures which will hopefully give us some clues to what is going on.
     
  10. Feb 3, 2012 #9

    DrDu

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    Well, already Pauli said "Festkoerperphysik ist eine Schmutzphysik".
    From a fundamental point of view, I don't understand why it should be absolutely necessary to study clean samples when the effect is already observable is the dirtiest samples from high school laboratories.
    As Anderson points out there is probably some renormalization involved so that only very few degrees of freedom are relevant anyhow.

    f95toli, do you know whether it is believed that the mechanism in other htc's like the arsenides are related?
     
  11. Feb 3, 2012 #10

    ZapperZ

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    People might want to read this overview of the cuprates by Mike Norman. He's a theorist and naturally, he summarizes the current theoretical understanding of the cuprates.

    http://arxiv.org/abs/1108.3140

    Zz.
     
  12. Feb 3, 2012 #11

    DrDu

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    Only 5 pages and no incomprehensible diagramms! Thank you ZapperZ!
     
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