XY-LIKE CRITICAL-BEHAVIOR OF THE THERMODYNAMIC AND TRANSPORT-PROPERTIES OF YBA2CU3O7-X IN MAGNETIC-FIELDS NEAR TC

The heat capacity, magnetization, and electrical conductivity of single-crystal samples of YBa2Cu3O7-x have been measured and are shown to support the existence of an intermediate critical regime in the vicinity of T(c), governed by the XY-like critical exponent nu congruent-to 2/3. Clear evidence is found for the divergence of the ohmic conductivity along the line H(m) (T) is-proportional-to (1 - T/T(c))2nu, the vortex melting line. The glass exponents along that line satisfy z(g)(nu(g)-1) congruent-to 6.