JOSEPHSON VORTEX LATTICE MELTING IN BI2SR2CACU2O8

The Josephson vortex lattice state of the highly anisotropic high-T-c superconductor Bi2Sr2CaCu2O8 has been probed by measurements of the ou t-of-plane (c-axis) resistivity as a function of temperature, current density, magnetic field strength H, and magnetic field orientation ang le theta. Anomalous dissipation is observed below a critical temperatu re identified as the melting transition of the Josephson vortex lattic e. The critical T-H and T-theta phase boundaries are determined. The m elting transition is interpreted as a Kosterlitz-Thouless depairing of interlayer vortex/anti-vortex pairs.