Condensed Matter Physics, 2008, vol. 11, No. 3(55), p. 495-507
Electronic spectrum and superconductivity in Hubbard model
(Joint Institute for Nuclear Research, 141980 Dubna, Russia; Max-Planck-Institut für Physik Komplexer Systeme, D-01187 Dresden, Germany)
(Joint Institute for Nuclear Research, 141980 Dubna, Russia; Rutgers University, Piscataway, New Jersey 08854, USA)
A microscopic theory of electronic spectrum and superconducting pairing within the Hubbard model is formulated. The Dyson equation for the normal and anomalous Green functions in terms of the Hubbard operators is derived by applying the Mori-type projection technique. The self-energy is evaluated in the noncrossing approximation for electron scattering on spin and charge fluctuations induced by kinematic interaction for Hubbard operators. Numerical results for electron dispersion in the strong correlation limit are presented. Superconducting pairing mediated by antiferromagnetic exchange and spin fluctuations is discussed.
strong electron correlations, Hubbard model, superconductivity
74.20.Mn, 71.27.+a, 71.10.Fd, 74.72.-h