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 ν⊥, ν∥ (≡ζν⊥), and z’ derived from the (d’+1)-dimension critical scaling of the frequency-dependent ac resistivity from 102 to 2.5×106 Hz. The Bose-glass transition temperature (TBG) is found to decrease with the increasing angle (θ) between the applied magnetic field and the c axis. The finding that ζ=ν∥/ν⊥=1.1±0.1