Phase Fluctuations and Single Fermion Spectral Density in 2D Systems with Attraction

TL;DR

This paper investigates how static phase fluctuations affect the spectral properties of 2D superconductors with attractive interactions, revealing non-Fermi liquid behavior and temperature-dependent broadening of quasiparticle peaks.

Contribution

It provides analytic expressions for the fermion Green's function and spectral density considering phase fluctuations, highlighting non-Fermi liquid effects in 2D systems.

Findings

Spectral density shows non-Fermi liquid behavior.

Quasiparticle peaks broaden with increasing temperature.

Analytic Green's function expressions derived for the model.

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 is studied. Analytic expressions for the fermion Green's function, its spectral density, and the density of states are derived in the approximation where the coupling between the spin and charge degrees of freedom is neglected. The resulting single-particle Green's function clearly demonstrates a 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.