Comparative studies of irreversibility lines and critical current in heavy ion irradiated Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+δ/ bicrystals with [001] twist grain boundaries

Columnar defects, through 2.2 GeV Au-ions irradiation, were introduced into Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+/spl delta// (Bi-2212) bicrystals with [001] twist grain boundaries. Studies of the effect of heavy ion irradiation on the transport properties of the bicrystals were performed by measuring the irreversibility line and critical current within the constituent single crystals and across the [001] twist grain boundaries before and after irradiation. We found that the columnar defects greatly increased the irreversible temperature determined both within the single crystals and across the grain boundaries. However, the enhancement on critical current by the columnar defects measured across the grain boundaries is not significant, while more than an order of magnitude increase in the single crystal critical current was observed.