VORTEX-FLUID DYNAMICS AND BOSE-GLASS ORDERING IN BI2SR2CACU2O8

The linear dynamic resistivity of thin films has been investigated bet ween 3mHz and 50MHz for flux densities ranging from 0.1mT to 12T. No t ransition from the vortex fluid to true superconductivity is found for the pristine samples down to resistivities as low as \rho\ approximat e to 10(-17)Omega cm. Columnar defects generated by heavy-ion irradiat ion, give rise to a Bose-glass transition between 0.1T and the matchin g field B-phi=1T. The transition line T-BG(B) agrees surprisingly well with the theoretical predictions for single-vortex pinning.