MAGNETIZATION CURRENT OF A THIN-LAYER OF BI1.8PB0.4SR2.0CA2.2CU3.0OY NEAR SILVER IN AG-SHEATHED BSCCO-2223 TAPES

The thin superconducting region next to the silver sheath in Ag-sheath ed BSCCO-2223 tapes, which appears to be the high critical current den sity region was studied. Magnetic hysteresis measurements were perform ed on the 10 mum thin layer of Bi1.8Pb0.4Sr2.0Ca2.2Cu3.0Oy near the si lver sheath as a function of temperature, intensity, and orientation o f the applied field with respect to the tape. The full penetration dep th, B, for a superconducting slab was found to have a power law depen dence on temperature. Correlating the magnetic and transport measureme nts for the 10 mum thin layer of Bi1.8Pb0.4Sr2.0Ca2.2Cu3.0Oy near the silver sheath showed that the 'self-field' for a transport critical cu rrent of 20 A at liquid nitrogen temperature was approximately 0.04 T. Magnetization currents as a function of temperature and applied field oriented parallel and orthogonal to the thickness dimension of the ta pe, J(c)(mu0H(app), T), were determined from the magnetization loop wi dth using a Bean model expression adapted for an orthorhombic sample. Only J(c)(mu0H(app), T) values for an applied magnetic field greater t han B were calculated. J(c) values that were one order of magnitude h igher than those previously reported were obtained.