Proton irradiation effects on critical current of bulk single-crystal superconducting YBCO wire

We have investigated the effects of 10 MeV proton irradiation on the magnetization M and critical current density J/sub c/ of bulk single-crystal YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) superconducting thick wire filaments produced through laser-heated floating zone (LHFZ) technique. M and J/sub c/ were determined both along the length and perpendicular to the length of the wire. Radiation-induced enhancement of J/sub c/ along the length of the wire was observed while there was a small decrease in J/sub c//spl perp/ to its length. J/sub c/ values along the length of the wire up to /spl sim/1.4/spl times/10/sup 5/ A/cm/sup 2/ at 77 K and /spl sim/1.3/spl times/10/sup 6/ A/cm/sup 2/ at 30 K and in applied magnetic field H=1 T were observed in the irradiated samples. In the unirradiated sample, the difference in magnetization /spl Delta/M at a given field in the magnetic hysteresis loop for increasing and decreasing field applied /spl perp/ to the sample length was observed to depend on the orientation of the sample about its axis. This indicates anisotropy in J/sub c/ along the sample length. This anisotropy increased on irradiation relative to the direction of irradiation. We believe that these J/sub c/ values along the length are amongst the highest published J/sub c/ values for bulk high temperature superconductor (HTS) thick wire filament.