Local order and the gapped phase of the Hubbard model: A plaquette dynamical mean-field investigationE. Gull1, P. Werner2, X. Wang2, M. Troyer1 and A. J. Millis2
1 Theoretische Physik, ETH Zurich - 8093 Zurich, Switzerland
2 Columbia University - 538 West, 120th Street, New York, NY 10027, USA
received 3 June 2008; accepted in final form 1 October 2008; published November 2008
published online 29 October 2008
The four-site “DCA” method of including intersite correlations in the dynamical mean-field theory is used to investigate the metal-insulator transition in the Hubbard model. At half-filling a gap-opening transition is found to occur as the interaction strength is increased beyond a critical value. The gapped behavior found in the 4-site DCA approximation is shown to be associated with the onset of strong antiferromagnetic and singlet correlations and the transition is found to be potential energy driven. It is thus more accurately described as a Slater phenomenon (induced by strong short-range order) than as a Mott phenomenon. Doping the gapped phase leads to a nonFermi-liquid state with a Fermi surface only in the nodal regions and a pseudogap in the antinodal regions at lower dopings x 0.15 and to a Fermi-liquid phase at higher dopings.
71.30.+h - Metal-insulator transitions and other electronic transitions.
71.27.+a - Strongly correlated electron systems; heavy fermions.
71.10.Fd - Lattice fermion models (Hubbard model, etc.).
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