Evidence for scaling invariance and universality of the irreversibility line of high temperature superconductors.

Measurements of the irreversibility line [ital H]([ital T][sup *]) of Y[sub 1[minus][ital x]]Pr[sub [ital x]]Ba[sub 2]Cu[sub 3]O[sub 6.97], a system in which the superconducting transition [ital T][sub [ital c]] can be varied from 0 to 92 K, show that [ital H]([ital T][sup *]) obeys a universal scaling relation characterized by an [ital m]=3/2 power law near [ital T][sub [ital c]], with a crossover to a more rapid temperature dependence below [ital T]/[ital T][sub [ital c]][approx]0.6. The applicability of the scaling formula to other high [ital T][sub [ital 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.