Strong-coupling features due to quasiparticle interactions in two-dimensional superconductors

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 similar to 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. (C) 1998 Elsevier Science B.V. All rights reserved.