EVIDENCE OF A BOSE-GLASS TRANSITION IN SUPERCONDUCTING YBA2CU3O7 SINGLE-CRYSTALS WITH COLUMNAR DEFECTS

Experimental evidence of a Bose-glass transition in the vortex state of YBa2Cu3O7 single crystals with columnar defects along the c axis is manifested by the universal critical exponents nu(perpendicular-to), v(parallel-to) (=zetanu(perpendicular-to)), and z' derived from the (d'+1)-dimension critical scaling of the frequency-dependent ac resistivity from 10(2) to 2.5x10(6) Hz. The Bose-glass transition temperature (T(BG)) is found to decrease with the increasing angle (theta) between the applied magnetic field and the c axis. The finding that zeta=nu(parallel-to)/mu(perpendicular-to) 1.1+/-0.1 < d'=2 suggests an incompressible Bose glass at temperatures below T(BG).