Pseudogaps in Strongly Correlated Metals: A generalized dynamical mean-field theory approach

TL;DR

This paper extends dynamical mean-field theory to include non-local correlations, enabling the study of pseudogap phenomena in strongly correlated metals through a generalized approach combining DMFT with a momentum-dependent self-energy.

Contribution

The authors develop a generalized DMFT+Sk method incorporating a momentum-dependent self-energy to account for non-local correlations in strongly correlated metals.

Findings

Pseudogap formation near the Fermi level observed in spectral functions.

DMFT+Sk reproduces pseudogap features consistent with experimental ARPES spectra.

Method applicable to doped Mott insulators and bandwidth-controlled metals.

Abstract

We generalize the dynamical-mean field (DMFT) approximation by including into the DMFT equations some length scale via a momentum dependent ``external'' self-energy S(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+Sk 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+Sk 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+Sk show a pseudogap formation near the Fermi level of the quasiparticle band.