FREQUENCY INDEPENDENCE OF THE VORTEX-GLASS TRANSITION IN YBA2CU3O7-DELTA THIN-FILMS

The frequency dependence of the vortex-glass phase transition in a YBa2Cu3O7-delta thin film was measured at frequencies ranging from 10(-1) to 10(5) Hz in applied fields H ranging from 0 to 50 kOe. The transition temperature T(g) and the critical scaling parameter nu(z - 1) were determined from the scaling of both current-voltage characteristics and the resistivity measurements. The critical scaling parameters determined by different methods are found to agree [nu(z - 1) = 7.2+/-0.3] and are consistent with the predictions of the continuous vortex-glass phase transition described by Fisher, Fisher, and Huse [Phys. Rev. B 43, 130 (1991)]. No frequency dependence is observed for the vortex-glass transition temperature T(g), for the range of parameters studied here. While the data do provide further support for the existence of a continuous vortex-glass phase transition, no evidence for the divergent time scale is observed, setting an upper limit of 10(-5) sec for this time scale at (T - T(g))/T(g) almost-equal-to 0.02. Since ac-susceptibility data do not actually measure the ''irreversibility line'' (IRL), these results provide a fundamental measurement of the frequency dependence of the IRL. The observed frequency dependence is inconsistent with the flux-creep-based picture of the IRL.