Flux motion and phase transitions in superconducting (K,Ba)BiO3 single crystals

We present magnetoresistance measurements up to 20 T performed on superconducting (K,Ba)BiO3 single crystals (T-c similar to 31 K). The foot of the transition curves can be fitted to rho-[H/H-g(T)-1](4.1) and the E-J curves exhibit a power law behavior at the melting temperature (E similar to J(3.2)). This shows that a vortex glass transition exists in this three-dimensional superconductor. The fluctuations of the conductivity in the vicinity of the mean field transition are discussed through the scaling procedure developed by Ullah and Dorsey. An H-T phase diagram has been deduced from the data.