Experimental comparison of the effect that bulk pinning and surface barriers have on vortex motion in the vortex liquid state of single crystals

We perform electrical transport measurements in the mixed state of (Formula presented) single crystals by using a Corbino disk geometry. In this configuration, vortices are forced to move in closed circular trajectories, without crossing the sample’s edge. By comparison with conventional four-probe transport experiments we can contrast the role that bulk pinning and surface barriers have on vortex motion in the vortex liquid state of this material. Our Corbino and conventional experiments give the same temperature and field dependence for the electrical resistivity in the vortex liquid state, activation energies for vortex motion and irreversibility lines. Thus, we conclude that in these crystals, flux motion in the vortex liquid state is governed by bulk effects.