345 research outputs found
Optical Conductivity in a Simple Model of Pseudogap State in Two-Dimensional System
We present calculation of optical conductivity in a simple model of
electronic spectrum of two-dimensional system with "hot patches" on the Fermi
surface, leading to non Fermi-liquid renormalization of the spectral density
(pseudogap) on these patches. It is shown that this model qualitatively
reproduces basic anomalies of optical experiments in the pseudogap state of
copper oxides.Comment: 12 pages, 6 figures, RevTeX 3.0, Postscript figures attache
Ginzburg-Landau Expansion in a Toy Model of Superconductor with Pseudogap
We propose a toy model of electronic spectrum of two-dimensional system with
``hot-patches'' on the Fermi surface, which leads to essential renormalization
of spectral density (pseudogap). Within this model we derive Ginzburg-Landau
expansion for both s-wave and d-wave Cooper pairing and analyze the influence
of pseudogap formation on the basic properties of superconductors.Comment: 14 pages, 14 figures, RevTeX 3.0, Postscript figures attached, some
changes in the explanation of the model, published in JETP 115, No.2, (1999
Generalized dynamical mean-field theory in physics of strongly correlated systems
This review is devoted to generalization of dynamical mean-field theory
(DMFT) for strongly correlated electronic systems towards the account of
different types of additional interactions, necessary for correct physical
description of many experimentally observed phenomena in such systems. As
additional interactions we consider: (1) interaction of electrons with
antiferromagnetic (or charge) fluctuations of order parameter in high-Tc
superconductors leading to the formation of pseudogap state, (2) scattering of
electrons on static disorder and its role in general picture of
Anderson-Hubbard metal-insulator transition, (3) electron-phonon interaction
and corresponding anomalies of electronic spectra in strongly correlated
systems. Proposed DMFT+Sigma approach is based on taking into account above
mentioned interactions by introducing additional self-energy Sigma (in general
momentum dependent) into conventional DMFT scheme and calculated in a
self-consistent way within the standard set of DMFT equations. Here we
formulate general scheme of calculation of both one-particle (spectral
functions and densities of states) and two-particle (optical conductivity)
properties. We examine the problem of pseudogap formation, including the Fermi
arc formation and partial destruction of the Fermi surface, metal-insulator
transition in disordered Anderson-Hubbard model, and general picture of kink
formation within electronic spectra in strongly correlated systems. DMFT+Sigma
approach is generalized to describe realistic materials with strong
electron-electron correlations based on LDA+DMFT method. General scheme of
LDA+DMFT method is presented together with some of its applications to real
systems. The LDA+DMFT+Sigma approach is employed to modelling of pseudogap
state of electron and hole doped high-T_c cuprates. Comparison with variety of
ARPES experiments is given.Comment: 60 pages, 24 figures. Review article accepted for publication in
Physics-Uspekh
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