The problem of crossover from BCS to Bose-Einstein condensation has recently attracted considerable interest
owing to the discovery of high-Tc cuprates. Their short coherence length, xi, places these materials in the
interesting region between BCS and Bose-Einstein condensation. In the paper of F. Pistolesi and G.C. Strinati (Phys. Rev. B 49, 6356, 1994), the Nozieres and Schmitt-Rink approach (NSR) is taken, which is valid for the weak coupling regime. They derive a relation between Tc and TF, which they insist is valid for any coupling strength. We present arguments that their assumptions are incorrect by using our fully self-consistent T-matrix formalism in two dimensions, and show that the NSR approach produces unphysical results in this case.
By: J. J. Rodriguez-Nunez (FEC-LUZ, Venezuela), S. Schafroth (Univ. Zurich, Switz.), T. Schneider, M. H. Pedersen (Univ. Zurich, Switz.) and C. Rossel
Published in: RZ2597 in 1994
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