INPLANE AND OUT-OF-PLANE TRANSPORT-PROPERTIES OF BI2SR2CACU2O8-FILMS - FLUCTUATIONS AND TRANSITION INTO A VORTEX SOLID-STATE(DELTA EPITAXIAL)

The in-plane (rho(ab)) and out-of-plane (rho(c)) resistivities of Bi2S r2CaCu2O8+x films have been simultaneously measured in magnetic fields parallel to the films c axis (B less than or equal to 1 T). The rho(a b)(T,B) and rho(c)(T,B) curves are well described both above and below the zero-field critical temperature by the fluctuation theory in the Hartree approximation, using a single set of microscopic parameters fo r both directions. This agreement extends down to temperatures at whic h the dissipation is usually attributed to vortex motion. In the low-t emperature region, however, both rho(ab) and p(c) exhibit a thermally activated behavior, and the I-V characteristics change from ohmic to n onohmic. We attribute this effect to the pinning-induced phase transit ion from a strongly fluctuating normal phase into a superconducting vo rtex solid phase.