Quasiparticle Properties of the Superconducting State of the Two Dimensional Hubbard Model

TL;DR

This paper uses cluster dynamical mean field methods to analyze quasiparticle properties and spectral features of the superconducting state in the two-dimensional Hubbard model, revealing insights into the pseudogap and spectral structures.

Contribution

It provides a detailed calculation of electron self energy components and spectral functions, elucidating the origin of the pseudogap and spectral features in the superconducting state.

Findings

Decreasing temperature in the pseudogap regime reduces the energy gap.

A 'peak-dip-hump' structure forms in the density of states.

The 'hump' arises from a zero crossing in the real part of the self energy.

Abstract

Cluster dynamical mean field methods are used to calculate the normal and anomalous components of the electron self energy of the two dimensional Hubbard model. From these the evolution of the superconducting gap and the momentum dependent photoemission and inverse photoemission spectra across the phase diagram are determined. In the pseudogap regime, decreasing the temperature into the superconducting state leads to a decrease in the energy gap and the formation of a `peak-dip-hump' structure in the electronic density of states. The peak feature disperses very weakly. The calculated spectral functions are in good qualitative agreement with published data. The mathematical origin of the behavior is found to be the effect of the superconductivity on the pole structure giving rise to the normal state pseudogap. In particular the "hump" feature is found to arise from a zero crossing of the real part of the electron self energy rather than from an onset of scattering. The effect of superconductivity on the zone diagonal spectra is presented.