Phase fluctuations in superconductors: From Galilean invariant to quantum XY models - art. no. 140506

We analyze the corrections to the superfluid density due to phase fluctuati ons within both a continuum and a lattice model for s- and d-wave supercond uctors. We expand the phase-only action beyond the Gaussian level and compa re our results with the quantum XY model both in the quantum and in the cla ssical regime. We find dynamic anharmonic vertices, absent in the quantum X Y model, which are responsible for the vanishing of the correction to the s uperfluid density at zero temperature in a continuum (Galilean invariant) m odel. Moreover, the phase-fluctuation effects are reduced with respect to t he XY model by a factor at least of order 1/(k(F)xi (0))2.