Quasiparticle interactions in two- and three-dimensional superconductors

Department of Physics, State University of New York, Buffalo, New York 14260, USA

Received: 25 July 1997
Accepted: 14 October 1997

Abstract


I investigate the difference between the quasiparticle properties in two-dimensional (2D) and three-dimensional (3D) s-wave superconductors. Using the original BCS model for the pairing interaction and direct Coulomb interaction I show that quasiparticle interactions lead to a stronger energy dependence in the single-particle self-energies in 2D than in 3D superconductors. This difference arises from the presence of the low-lying collective mode of the order parameter in the 2D case which ensures that oscillator strength in the response function is at low frequencies, . This strong quantitative difference between 2D and 3D superconductors points to the importance of treating quasiparticle interactions in low-dimensional superconductors rather than assuming that renormalizations remain unchanged from the normal state.