BOSE-GLASS TRANSITION IN THIN YBA2CU3O7-DELTA FILMS

We report on the thermodynamic phase transition to truly superconducti ng glassy vortex states in thin YBa2Cu3O7-delta films before and after heavy ion irradiation. By dynamic scaling analyses of the ac-conducti vity sigma(omega) measured over a broad frequency range, we determine the transition lines, T-g(B), and the critical exponents for the glass correlation length and time. All quantities reveal Bose-glass localiz ation of single vortices up to the matching field (B-phi = 1T), which appears to be related to the strong pristine disorder in the films.