Effect on c-axis transport properties of a critical state in Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8/ single crystals

At low temperatures, the c-axis transport properties of Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8/ single crystals depend strongly on the magnetic field history for fields applied along the c-axis, indicating the effect of a critical state in the ab direction. In this study, we report zero field cooled (ZFC), field cooled warming (FCW), and field cooled cooling (FCC) c-axis transport properties. In addition, we also report magnetic relaxation measurements on the same samples to identify the c-axis dissipation mechanism. We observe a relaxation of the c-axis resistivity that follows the relaxation of the flux profile across the ab plane. By identifying the irreversible temperature vs magnetic field for H/spl par/c, we construct a phase diagram of vortex states. Finally, we will discuss the implication of the phase diagram and the features related to the transport properties of the Josephson-coupled system and the role of pancake vortices in highly two-dimensional superconductors.<>