Weakly correlated superconductors

A concept of weak correlation in superconductors is introduced, which is similar, but not equal, to weak coupling (of the Josephson type), and some consequences of the idea are briefly considered. It is shown that the dependence of critical temperature of layered superconductors on the number of layers may be explained taking into account the correlation energy, and may not be accounted for by the Josephson model (neglecting correlation). (author)