Strong-Coupling Features Due to Quasiparticle Interaction in Two Dimensional Superconductors

TL;DR

This paper investigates how quasiparticle interactions in two-dimensional superconductors lead to strong-coupling effects, explaining experimental observations in cuprate superconductors beyond traditional theories.

Contribution

It provides a calculation showing that quasiparticle interactions in 2D superconductors cause significant strong-coupling effects, unlike in 3D, offering insight into cuprate superconductor data.

Findings

Quasiparticle interactions are enhanced at low frequencies in 2D due to gapless plasmons.

Strong-coupling effects are more prominent in 2D than in 3D superconductors.

The results explain experimental features observed in cuprate superconductors.

Abstract

I calculate the effect of interactions among superconducting quasiparticles in two-dimensional(2D) a superconductor at T=0. The strength of the effective interaction among the quasiparticles is essentially given by the screened Coulomb interaction which has strength at low frequency because of the gapless nature of the plasmon. This is in contrast to three dimensions where the effective interaction has negligible weight at frequencies $\sim \Delta$, the superconducting gap. The quasiparticle interactions give rise to strong-coupling effects in experimental quantities which are beyond the conventional Eliashberg treatment of superconductivity. The present calculation offers an explanation of why these effects are much larger in 2D than in 3D superconductors and, in particular, why the analogous strong-coupling effects due to quasiparticle interactions are seen in data on the quasi-2D cuprate superconductors. the strong-coupling features seen in data on the cuprates are discussed in light of the present calculation.