EFFECT OF PHASE FLUCTUATIONS ON THE LOW-TEMPERATURE PENETRATION DEPTH OF HIGH-T-C SUPERCONDUCTORS

We describe a simple model to estimate the effects of order parameter phase fluctuations on the penetration depth (T) of high- Tc superconductors. When treated classically, such fluctuations are found to produce a linear temperature dependence of (T), which may be comparable to the experimentally observed magnitude. This dependence persists when the combined effects of charging interactions and dissipation are included in the model. Hence, such a dependence may not be a unique signature of a superconductor with line nodes at the Fermi surface. © 1995 The American Physical Society.