Models of the Pseudogap State of Two-Dimensional Systems

TL;DR

This paper investigates solvable models of two-dimensional electronic systems exhibiting pseudogap states due to short-range order fluctuations, providing detailed spectral and density of states analysis.

Contribution

It introduces a recurrence method to compute Green's functions considering all perturbation diagrams, advancing understanding of pseudogap phenomena in 2D systems.

Findings

Spectral densities show anisotropic pseudogap formation.

Density of states reveals pseudogap features.

Method accounts for all perturbation series diagrams.

Abstract

We analyze a number of ``nearly exactly'' solvable models of electronic spectrum of two-dimensional systems with well-developed fluctuations of short range order of ``dielectric'' (e.g. antiferromagnetic) or ``superconducting'' type, which lead to the formation of anisotropic pseudogap state on certain parts of the Fermi surface. We formulate a recurrence procedure to calculate one-electron Green's function which takes into account all Feynman diagrams in perturbation series and is based upon the approximate Ansatz for higher-order terms in this series. Detailed results for spectral densities and density of states are presented. We also discuss some important points concerning the justification of our Ansatz for higher-order contributions.