EVIDENCE FOR SCALING INVARIANCE AND UNIVERSALITY OF THE IRREVERSIBILITY LINE OF HIGH-TEMPERATURE SUPERCONDUCTORS

Measurements of the irreversibility line H(T*) of Y1-xPrxBa2Cu3O6.97, a system in which the superconducting transition temperature T(c) can be varied from 0 to 92 K, show that H(T*) obeys a universal scaling relation characterized by an m = 3/2 power law near T(c), with a crossover to a more rapid temperature dependence below T/T(c) almost-equal-to 0.6. The applicability of the scaling formula to other high T(c) superconductors is tested, with the results suggesting that both the crossover phenomenon and the power law temperature dependence are ubiquitous, scale-invariant properties of high temperature superconductors.