Local J/sub c/ distribution in superconducting oxide layer of Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x//Ag tapes

Abstract

The relationship between critical current (I/sub c/) and the thickness of oxide layer of Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/(Bi-2212)/Ag composite superconductor has been studied to clarify local critical current density (J/sub c/) distribution in the oxide layer. The comparison of local J/sub c/ (J/sub c//sup local/) distribution of the samples prepared with and without PAIR (P_re-A_nnealing and I_ntermediate R_olling) process gives an explanation for the large J/sub c/ enhancement by PAIR process. J/sub c/ of oxide layer within 2 /spl mu/m from the Bi-2212/Ag interface exceeds 3.8/spl times/10/sup 5/ A cm/sup -2/ at 4.2 K, 10 T. No significant increase of J/sub c//sup local/ is confirmed in the Bi-2212 layer below 2 /spl mu/m from the interface. However, J/sub c//sup local/ increases by performing PAIR process in the middle part of the Bi-2212 layer of 2-15 /spl mu/m from the interface. J/sub c//sup local/ is 2.4/spl times/10/sup 5/ A cm/sup -2/ and 1.0/spl times/10/sup 5/ A cm/sup -2/ at a distance of 5 pm and 10 /spl mu/m from the interface, respectively. The results indicate that the large J/sub c/ enhancement by PAIR process is assigned to higher J/sub c//sup local/ in this middle part. J/sub c/ improvement in the part near the free surface is also achieved by PAIR process and contributes to high J/sub c/.