FLUX-FLOW AND PHASE-SLIP DISSIPATION IN CRYSTALLINE BI2SR2CACU2O8+DELTA AND YBA2CU3O7-DELTA

We have employed a microwave technique to determine the temperature dependences of dissipative mechanisms in textured polycrystalline Y 123 and in single phase crystalline BSCCO. The measurements were carried out over the temperature range of 5-100 K, with the applied magnetic field typically varying to a maximum of 1.9 T, applied parallel to the c-axis. The RF current was in the c-plane. In addition to small flux-flow signals, a thermally activated field dependent signal, which apparently arises from phase-slip in a network of weak links, was identified. Phase-slip resistivity is the dominant loss mechanisms near T(c). The data have been successfully fit to an extension of a theory of Tinkham, yielding estimates of the phase-slip pinning energy and H(c2).