Modification of bulk properties of Bi/sub 1.8/Pb/sub 0.33/Sr/sub 1.87/Ca/sub 2/Cu/sub 3/O/sub y/ tapes by means of ion induced surface trenches

This paper demonstrates the possibility to enhance predictably the behavior of the superconducting properties in a bulk material, by introducing linearly correlated defects within a surface layer. Columnar defects, having a depth of about 5% of the total thickness of the sample, were created on Ag/BSCCO-2223 tapes by means of 0.25 GeV Au ions at different fluences, with a dose equivalent field B/sub /spl phi// ranging from 1 T to 5 T. The implantation depth was about 15% of the total thickness of the sample. The shape and position of the irreversibility lines were deeply modified. The vortex dynamics, as investigated by a.c. susceptometry in d.c. magnetic field, exhibits features characteristics of Bose-glass like localization in a range of field between the onset of the localized phase and the dose equivalent field. From all the experimental data it emerges that the strategy of creating surface trenches for vortices is always largely effective in this range of magnetic fields.