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BCS theory

  1. Oct 6, 2009 #1
    In the theory of superconductivity BCS theory is given eigen - problem


    Why [tex]E+2\frac{\hbar^2k^2_F}{2m}[/tex]?

    Maybe because is Fermi sphere is centered in origin?
  2. jcsd
  3. Oct 8, 2009 #2


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    This is just a convenient redefinition of the zero of energy. There are two electrons involved in the pair so it is convenient to measure energy with respect to *twice* the Fermi energy. Where the Fermi energy is supposed to be given in terms of the Fermi momentum [itex]k_F[/itex] by
  4. Nov 6, 2009 #3
    Is there a clear boundary between low temperature and high temperature superconductors? Is it maybe 40K? I ask because BCS theory is theory for low temperature superconductors. And from this theory we know that the energy of bond of Cooper pair is


    where [tex]WN(0)<<1[/tex]
  5. Nov 6, 2009 #4
    Yes, above 30K anything is considered high Tc superconductivity, because that's the predicted upper limit of BCS theory.

    Müller and Bednorz received 1986 Nobel prize immediately after discovering a ceramic structure with Tc=35K.
  6. Nov 6, 2009 #5


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    In low temperature superconductors it is thought that phonons make up the "glue" for the Cooper pairs (hence the \omega_D in your formula, etc). In high temperature superconductors the "glue" is thought to be something else...
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