We have recently proposed a Strongly Correlated Superconductivity (SCS) scenario which deals with the question whether and under which conditions Cooper-pairing may be favoured by strong electron repulsion close to a Mott transition. The core of the SCS proposal is that the effective repulsion between quasiparticles vanishes close to the Mott transition, while a pairing attraction which involves spin and orbital degrees of freedom remains unrenormalized. Under these conditions, the superconducting order parameter may be hugely enhanced by approaching the Mott transition. This scenario has been originally demonstrated through a Dynamical Mean Field Theory (DMFT) solution of a three-band Hubbard model for s-wave superconducting fullerenes [1]. Recently we extended the SCS scenario to a twofold orbitally degenerate model with inverted Hund’s rule exchange. Solving the model as a function of density, we obtain an extremely appealing phase diagram, where superconductivity arises by doping the Mott insulator, out of a pseudogapped metallic phase, very much as it happens in cuprates. In the final part of the talk I will discuss the extension of this scenario to d-wave superconductors.
[1] M. Capone, M. Fabrizio, C. Castellani, and E. Tosatti, Science Vol. 296, 2364 (2002).
[2] M. Capone, M. Fabrizio, C. Castellani, and E. Tosatti, Phys. Rev. Lett. 94 047001 (2004).

Istituto CNR dei Sistemi Complessi and Universita di Roma “La Sapienza”