Scaling of vortex transport properties in high-temperature superconductors

Using both dc and low-frequency-ac (10105 Hz) transport measurements in low magnetic fields (06.3 kOe), we find that the vortex transport properties of YBa2Cu2.98Au0.02Ox (x=6.97±0.02) single crystals are consistent with a three-dimensional second-order vortex solid melting transition, with a static exponent 1/2=0.9±0.2, a dynamic exponent z=2.0±0.2, and a characteristic current-density exponent 1/4=0.5±0.1. In contrast, transport properties of epitaxial films generally agree with the Ambegaokar-Halperin model. © 1992 The American Physical Society.