D-wave superconductivity in the nearly antiferromagnetic fermi liquid

Abstract

Self consistent calculations, based on the 2 dimensional Hubbard model, indicate that the nearly antiferromagnetic Fermi liquid may be a superconductor with dx2-y2 symmetry. The recent observation of a large anisotropy of the in plane penetration depth has been widely interpreted as evidence that a significant part of the condensate in YBa2Cu3O7−gd resides in the chains. This introduces orthorhombic symmetry. Calculations, which remain within a single tight binding band model but with different nearest neighbour hopping in a- and b-directions, can account for the penetration depth anisotropy and also explain the observed size of the D.C. Josephson current between YBa2Cu3O7−gd and Pb in c-axis tunnelling.