Quintanilla, Jorge and Gyorffy, Balazs L.
Cooper pairing with finite angular momentum: BCS versus Bose limits.
Journal of Physics A: Mathematical and General, 36
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PDF (Quintanilla and Gyorffy, J. Phys. A - Math Gen. (2003))
We revisit the old problem of exotic superconductivity as Cooper pairing with finite angular momentum emerging from a central potential.
Based on some general considerations, we suggest that the phenomenon
is associated with interactions that keep electrons at some particular,
finite distance r(0), and occurs at a range of intermediate densities
n similar to 1/r(0)(3). We discuss the ground state and the critical
temperature in the framework of a standard functional-integral theory
of the BCS to Bose crossover. We find that, due to the lower energy
of two-body bound states with l = 0, the rotational symmetry of the
ground state is always restored on approaching the Bose limit. Moreover
in that limit the critical temperature is always higher for pairs
with l = 0. The breaking of the rotational symmetry of the continuum
by the superfluid state thus seems to be a property of weakly-attractive,
non-monotonic interaction potentials, at intermediate densities.
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