Critical fluctuations and pinning effects on the vortex transport in superconducting Y-Ba-Cu-O single crystals

The critical fluctuations and pinning effects in the vortex state of twinned superconducting Y-Ba-Cu-O single crystals are investigated. A second-order vortex-solid melting transition is manifested by the universal static and dynamic exponents ν2/3 and z3 and the universal vortex-transport functions, independent of the experimental techniques and the magnitude and orientation of the applied magnetic fields. The vortex-correlation length and the critical-relaxation rate are also determined. © 1993 The American Physical Society.