Flux motion and phase transitions in superconducting (K,Ba)BiO3single crystals

We present magnetoresistance measurements up to 20 T performed on superconducting (K,Ba)Bi${\mathrm{O}}_3$ single crystals ($T_c\sim 31$ K). The foot of the transition curves can be fitted to $\rho \sim {[\frac{H}{H_g\mathrm{}\left(T\right)\mathrm{}}-1]}^{4.1}$ and the $E-J$ curves exhibit a power law behavior at the melting temperature ($E\sim J^{3.2}$). 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.