Superconductive states with odd angular momentum pairing in the 2D repulsive Hubbard model

Abstract

The earlier suggested superconductive state in the two-dimensional repulsive Hubbard model is investigated. Cooper pairing in this state arises due to an effective attraction of fermions in channels with odd angular momenta. It is shown that superconductivity can exist only if one of the Van Hove saddle points of the quasiparticle energy lies near the Fermi level. Equations are obtained for the phase transition curve and for the order parameter in the superconductive state. The optimal relative position of the Van Hove point and the Fermi level corresponding to the maximal critical temperature is found. It is argued that two superconductive modes with threefold spin degeneration and, in principle, with different values of the gap parameter can exist in the model under consideration.