Pseudogaps in Strongly Correlated Metals

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We generalize the dynamical-mean field (DMFT) approximation by including into the DMFT equations some length scale via a (momentum dependent) ``external'' self-energy Σ_k. This external self-energy describes non-local dynamical correlations induced by short-ranged collective SDW-like antiferromagnetic spin (or CDW-like charge) fluctuations. At high enough temperatures these fluctuations can be viewed as a quenched Gaussian random field with finite correlation length. This generalized DMFT+Σ_k approach is used for the numerical solution of the weakly doped one--band Hubbard model with repulsive Coulomb interaction on a square lattice with nearest and next nearest neighbour hopping. The effective single impurity problem in this generalized DMFT+Σ_k is solved by numerical renormalization group (NRG). Both types of strongly correlated metals, namely (i) doped Mott insulator and (ii) the case of bandwidth W<=U (U - value of local Coulomb interaction) are considered. Densities of states, spectral functions and ARPES spectra calculated within DMFT+Σ_k show a pseudogap formation near the Fermi level of the quasiparticle band.
35 pages, 16 figures

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Strongly Correlated Electrons

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http://salesiana.dossiersoluciones.com/handle/123456789/136858

Consulte el texto completo en el siguiente enlace:

https://arxiv.org/abs/cond-mat/0502612
 http://arxiv.org/abs/cond-mat/0502612
 Phys. Rev. B 72, 155105 (2005)

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arXiv