Flux pinning and dissipation in textured multifilamentary (Bi-Pb)₂Sr₂Ca₂Cu₃O_x/Ag tapes

We have studied the magnetotransport, magnetization properties, and microstructure of multifilamentary (Bi-Pb)₂Sr₂Ca₂Cu₃O_x (Bi-2223)/Ag tapes with varying filaments from 1 to 37 to explore the energy dissipation, reversible flux motion, and flux pinning related to the microstructure. Our results show that the dissipation is temperature, current, and magnetic field induced. The dissipation is thermally activated and the vortex liquid state is plastically deformed. The dissociation of vortex-antivortex pairs by current, magnetic field, and temperature plays a major role in enhancing the dissipation process, resulting in large broadening in the transition. We observed a reversible fluxoid motion of vortices. The critical current density follows an exponential dependence on the magnetic field. The weak links seem to be broken even for a field as low as 5 G even 12 K below the transition temperature. However, at low temperature, the weak links behave as superconducting. The microscopic characterizations show evidence for the dislocations, stacking faults, and misorientation of grains and grain boundaries that control the critical current in tapes.