PHASE-SLIP DISSIPATION AND DIMENSIONALITY ABOVE THE IRREVERSIBILITY LINE IN BI2SR2CACU2O8+X

The analysis of several sets of data for the resistivity in Bi2Sr2CaCu 2O8+x films, measured as a function of the temperature, the magnetic f ield, and the field orientation, allows us to show that a phase-slip-d issipation model is able to accurately describe the experimental resul ts when the fluxon thermal fluctuations are governed by a glasslike ac tivation law A/[T-T-8(H)], where T-8(H) is the irreversibility line. I n this framework, we obtain the temperature and magnetic-field depende nce of the quasi-activation-energy A. A qualitative explanation is giv en for the temperature and magnetic behavior in terms of a 3D-2D cross over due to the softening of the flux lines with increasing field.