Nodal quasiparticles and classical phase fluctuations in d-wave superconductors

TL;DR

This paper demonstrates that nodal quasiparticles significantly influence classical phase fluctuations in d-wave superconductors, leading to singularities and invalidating the classical XY-model at low temperatures.

Contribution

It reveals the impact of nodal quasiparticles on phase fluctuations, showing the inadequacy of the XY-model for d-wave superconductors at low temperatures.

Findings

Nodal quasiparticles cause singularities in phase fluctuation behavior.

Classical XY-model is insufficient for describing low-temperature fluctuations.

Significant effect of quasiparticles on coupling constants in the effective action.

Abstract

We show that the nodal quasiparticles have significant effect on the classical phase fluctuations in a quasi-two-dimensional d-wave superconductor. They give rise to singularities in the temperature behavior of some of the coupling constants in the phase-only effective action. One of the consequences is that the classical XY-model is not adequate for the description of the superconducting fluctuations in d-wave superconductors at low temperatures.