INFLUENCE OF COLUMNAR DEFECTS ON VORTEX DYNAMICS IN BI2SR2CACU2O8 FROM OUT-OF-PLANE AND FLUX TRANSFORMER TRANSPORT MEASUREMENTS

he c-axis resistivity, rho(c)(B,T,theta), where theta is the angle bet ween the c axis and the dc field, has been measured for Bi2Sr2CaCu2O8 single crystals before and after the introduction of columnar defects by heavy ion irradiation. The effects of different columnar track dens ity and angle with respect to the basal plane are also investigated. U niaxial enhancement of the irreversibility line for fields below the m atching field and parallel to the columnar defects is observed in out- of-plane transport measurements. Measurements in the flux transformer geometry confirm that the vortices are connected lines in the irradiat ed crystal. We have also attempted to reconcile c-axis data with the p redictions of the Bose-glass theory for correlated disorder.