Magnetoresistance and V-I curves of Ag-sheathed (Bi,Pb)2Sr2Ca2Cu3O10+y tape

The magnetoresistance and the V-I curves (I>Ic) of a well-characterized Ag-clad (Bi,Pb)2Sr2Ca2Cu3O10+y tape (BPSCCO) with Jc(77 K, B=0)=10 kA/cm2 have been analyzed in the temperature (T) range 80–110 K and magnetic field (B) up to 60 mT. The results obtained after the correction for the parallel conduction through the Ag sheathing and BPSCCO core are similar to those for corresponding single crystals and the epitaxial thin films. The effective activation energy for the flux creep U0 is larger than those for the single crystals and thin films of Bi-Sr-Ca-Cu-O (BSCCO) compound. The variations of the differential resistance Rf (deduced from V-I curves at I≫Ic) with T and B are consistent with those for the conventional type-II superconductors at elevated temperatures and low fields. Hence the unusual features deduced from the total dissipation in similar tapes are probably due to improper data analysis. The analysis presented here relies on the homogeneity of dissipation within the core which has to be checked for each tape.