MAGNETIC-FIELD DEPENDENT MICROWAVE-ABSORPTION EVIDENCE FOR A MIXED LIQUID-SOLID VORTEX PHASE IN BI2SR2CACU2O8+X

The depinning of vortices can be observed as a change in the slope of the dependence of the surface resistance on B-1/2. However, close to t he transition magnetic field it is observed that there is a departure from the B-1/2 dependence. It is shown that this deviation is inconsis tent with second order behavior associated with a vortex glass. The de viation, however, can be accounted by the existence of a mixture of so lid and vortex liquid phases resulting from a magnetic field dependent distribution of pinning barriers.