LINEAR TEMPERATURE-DEPENDENCE OF PENETRATION DEPTH DUE TO PHASE FLUCTUATIONS

We describe a simple model to estimate the effects of order parameter phase fluctuations on the penetration depth of high-T-c superconductor s. Classical phase fluctuations are found to produce a linear temperat ure-dependence of the penetration depth, which may be comparable to th e experimentally observed magnitude. We also study how this behavior i s modified when the phase fluctuation energy is treated quantum-mechan ically.