Hall angle and vortex phases in thin films

We investigated the magnetic-field dependence of the Hall angle (Formula presented) for (Formula presented) thin films. We found that a crossover field (Formula presented) which is obtained from the field dependence of (Formula presented) coincides with the crossover line that is obtained for longitudinal transport and that divides the thermally activated flux-flow region from the critical region. The effective activation energy (Formula presented) at the critical region increases very rapidly with decreasing temperature. To clarify the details of the vortex phase diagram in the (Formula presented) plane, we extensively studied the Hall angle and the effective activation energy. In addition to the above two regions, the Hall angle was studied in the free flux-flow region, and the measured Hall angle satisfied (Formula presented) where (Formula presented) strongly depended on T and (Formula presented) showed a weak T dependence.