Critical state of the weakly coupled two-dimensional superconductor Bi2Sr2CaCu2O8

Transport measurements show that the critical current in the c direction, Jcc of Bi2Sr2CaCu2O8 single crystals increases with temperature for low temperature zero field cooled (ZFC) measurements. As a consequence, the c direction electrical resistance of the ZFC critical state, at a given dc current, is finite, goes to zero with increasing temperature, and becomes finite again at higher temperatures. The results are consistent with a loss of the c axis long range correlation induced by the critical current flowing in the ab planes, Jcab, and an increase of that correlation with temperature, as a consequence of the corresponding decrease of Jcab.