Pairfield Fluctuations of the 2D Hubbard Model

TL;DR

This study investigates the nature of pairfield fluctuations in a 2D Hubbard model at various dopings, revealing different fluctuation regimes above the transition temperature related to pseudogap presence.

Contribution

It distinguishes between Emery-Kivelson phase fluctuations and Gaussian amplitude fluctuations in the pairfield susceptibility depending on doping levels.

Findings

Evidence for Kosterlitz-Thouless fluctuations near transition

Emery-Kivelson phase fluctuations in pseudogap regime

Gaussian amplitude fluctuations in non-pseudogap regime

Abstract

At temperatures above the superconducting transition temperature the pairfield susceptibility provides information on the nature of the pairfield fluctuations. Here we study the d-wave pairfield susceptibility of a 2D Hubbard model for dopings which have a pseudogap (PG) and for dopings which do not. One knows that in both cases there will be a region of Kosterlitz-Thouless fluctuations as the transition at $T_{KT}$ is approached. Above this region we find evidence for Emery-Kivelson phase fluctuations for dopings with a PG and Gaussian amplitude fluctuations for dopings without a PG.