REACHING THE UNREACHABLE - CRITICAL SCALING AT THE SUPERCONDUCTING TRANSITION

The large coherence length of conventional superconductors causes the critical region near Tc to be unobservably small, leading to the impre ssion that mean-field theory can adequately explain properties near th e transition. The high-temperature superconductors, however, have such strongly type-II character that the critical, or at least an intermed iate critical, region is experimentally accessible. We demonstrate the applicability of XY-like critical scaling to magnetization, heat capa city and conductivity data and through the fitting parameters, make co ntact with a strong-coupling calculation of the critical temperature. Further, the scaled conductivity data show clear evidence for a thermo dynamic transition along the freezing line H(m)(T) is-proportional-to (1 - T/T(c))4/3.