EFFECT OF COLUMNAR DEFECTS ON THE VORTEX DYNAMICS IN BSCCO-2212 SINGLE-CRYSTALS

The form of the dynamic relaxation of high quality BSCCO 2212 single c rystals irradiated with 2.25 GeV Au ions to produce columnar defects a long the crystallographic c-axis, is reported. It is found that below 10K, the columns do not significantly inhibit flux motion once the vor tex density exceeds the column density. Above 10K, and at low vortex d ensities, the columns depress the dynamic behaviour in a systematic wa y as a function of temperature. At high vortex densities, the columns are decreasingly effective as the temperature is raised and in a manne r which is a non linear function of irradiation dose.