Superconductivity in oxides: from strong to weak coupling

F. Marsiglio and J.E. Hirsch, Physica C 165,71, (1990)

It is proposed that an essential feature of the superconductivity of high-Tc oxides is a cross-over from strong to weak coupling regimes as the hole concentration increases. This cross-over is a necessary consequence of the mechanism of hole superconductivity recently proposed, and it leads to clear observable consequences. In particular, an unusual feature obtained is that the quasi-particle gap is non-zero at Tc for low hole concentration.