Abstract
For a dilute gas of fermions interacting via an arbitrary pair potential in d=2 dimensions, we show that the many-body ground state is unstable to s-wave pairing at T=0 if and only if a two-body bound state exists. We further obtain, within a variational pairing Ansatz, a smooth crossover from a Cooper-paired state (≫1) to a Bose condensed state of tightly bound pairs (≪1). We briefly discuss non–s-wave superconductors. Insofar as this model is appli- cable to the high- materials, they are in the interesting regime with the coherence length comparable to the interparticle spacing .
- Received 4 November 1988
DOI:https://doi.org/10.1103/PhysRevLett.62.981
©1989 American Physical Society