Phase fluctuations and Non-Fermi Liquid Properties of 2D Fermi-system with attraction

TL;DR

This paper investigates how static phase fluctuations in a 2D attractive Fermi system lead to non-Fermi liquid behavior and pseudogap phenomena, with analytic expressions for Green functions and spectral density.

Contribution

It provides analytic derivations of Green functions and spectral densities showing non-Fermi liquid behavior caused by phase fluctuations in 2D superconductors.

Findings

Quasiparticle peaks broaden with temperature increase.

The gap in the quasiparticle spectrum persists despite broadening.

Dynamical fluctuations fill the gap, explaining pseudogap behavior.

Abstract

The effect of static fluctuations in the phase of the order parameter on the normal and superconducting properties of a 2D system with attractive four-fermion interaction has been studied. Analytic expressions for the fermion Green function, its spectral density and the density of states are derived. The resultant single-particle Green function clearly demonstrates non-Fermi liquid behavior. The results show that as the temperature increases through the 2D critical temperature the width of the quasiparticle peaks broadens significantly. At the same time one retains the gap in quasiparticle spectrum. The spectral density for the dynamical fluctuations can also be obtained. Clearly the dynamical fluctuations fill the gap giving the observed pseudogap behaviour.