Microscopic description of d-wave superconductivity by Van Hove nesting in the Hubbard model

5 págs.; 3 figs.; 3 tabs. ; PACS number(s): 74.20.Mn, 71.27.1a, 71.10.FdWe devise a computational approach to the Hubbard model that captures the strong coupling dynamics arising when the Fermi level is at a Van Hove singularity in the density of states. We rely on an approximate degeneracy among the many-body states accounting for the main instabilities of the system (antiferromagnetism, d-wave superconductivity). The Fermi line turns out to be deformed in a manner consistent with the pinning of the Fermi level to the Van Hove singularity. For a doping rate δ∼0.2, the ground state is characterized by d-wave symmetry, quasiparticles gapped only at the saddle points of the band, and a large peak at zero momentum in the d-wave pairing correlations. ©2000 American Physical SocietyThis work has been partially supported by the Ministerio de Educación y Cultura Grant No. PB96-0875.Peer Reviewe