VORTEX STATE AND FLUX-PINNING IN BI2223 AG TAPE/

The resistivity and critical current density Jc of an almost single ph ase Ag-clad (Bi,Pb)(2)Sr2Ca2Cu3O10-y (hereafter Bi2223) tape have been measured in the temperature (T) range 77-120K and magnetic field (B) up to 1T. Within the explored T and B range, J(c)(B) and the pinning e nergy U(B) obey the relation UJ(c) proportional to 1/B predicted by th e Larkin-Ovchinnikov theory of the collective pinning. The observed, v ery low maximum pinning force densities F-pmax = (J(c)B)(max) in Bi222 3 tapes are explained in terms of the percolative current flow in thes e materials. The implications of these findings on the study of vortex states in Bi2223 tapes are briefly discussed.