Current-induced decoupling of vortices in Bi(2)Sr2CaCu(2)O(8)

Simultaneous transport and magnetization measurements in Bi2Sr2CaCu2O8 crys tals are reported. The transport current is injected at the top surface, wh ile Hall sensor arrays measure the local magnetic field across the crystals at the bottom. Surprisingly, at high-currents we find finite resistivity w ell below the magnetic irreversibility line, where the vortices are pinned. This resistivity is non-monotonic with temperature and highly non-linear. We interpret the new observation as a shear-induced decoupling, in which th e vortices flow only in the top few layers and are decoupled from the pinne d vortices in the rest of the crystal. (C) 2000 Elsevier Science B.V. All r ights reserved.