Vortices in weakly coupled layered superconductors

The vortex system in high-temperature layered superconductors exhibits a ri ch phase diagram with many proposals of phase transitions modifying the cor relations both within and between the layers, We focus on the limit where t he magnetic coupling between "pancake" vortices dominates over the interlay er Josephson coupling. The wear;, but long-ranged nature of this magnetic i nteraction allows for an accurate "mean-field" treatment where the pancakes in each layer move independently in a self-consistent substrate potential. We calculate the form of the two relevant phase transitions in this system . First, we determine when the substrate potential is too weak to stabilize the two-dimensional (LD) fluctuations and the lattice evaporates to a panc ake gas. Second, within the lattice Eve find a Kosterlitz-Thouless unbindin g transition of vacancies and interstitials. For a small but finite Josephs on term, this is identified with the phase-decoupling transition. (C) 2000 Elsevier Science B.V. All rights reserved.