Multiterminal measurements of vortex correlations in the (K,Ba)BiO3 system

We have studied vortex correlations in single crystals of Ba1-xKxBiO3 by me ans of multiterminal transport measurements in magnetic fields up to 12 T. The pseudo flux-transformer geometry was used to probe the vortex correlati ons in the vortex liquid as a function of temperature and field. The vortex system is found to be correlated over the sample thickness just above the onset of resistivity for low to intermediate applied fields. The observed l oss of vortex correlation at higher fields is attributed to pinning.