Single-Particle Excitations in a Two-Dimensional Strong-Coupling Superconductor

TL;DR

This paper investigates the single-particle excitation spectrum in a two-dimensional strong-coupling superconductor, revealing how Cooper-pair fluctuations suppress low-energy excitations near the transition.

Contribution

It introduces a self-consistent calculation of the excitation spectrum and electromagnetic response in a 2D strong-coupling superconductor, highlighting the role of fluctuations.

Findings

Spectral weight at low frequency decreases approaching the transition

Cooper-pair fluctuations significantly suppress low-energy excitations

Electromagnetic response indicates superfluid density and transition temperature

Abstract

We present calculations of the single-particle excitation spectrum for a 2D strong-coupling superconductor in a conserving approximation. Spectral weight at low frequency is substantially reduced as the superconducting transition is approached from the normal state. The suppression of low-energy excitations is a consequence of Cooper-pair fluctuations that are described self-consistently in the fluctuation exchange approximation. The static and uniform electromagnetic response provides a measure of the super fluid density and a fully self-consistent indication of the superconducting transition temperature.