Nojima and Fujita have found a universal relation, irrespective of temperatures T, between the reduced field hH/Hir(T) and the reduced quantity of magnetization hysteresis mΔM (T, H)/ΔM (T, H0), where Hir is the irreversibility field and ΔM(T, H) is the hysteresis of magnetization for YBa2Cu3Ox and Bi2Sr2CaCu2Ox films. We could explain this universal relation based on a scaling theory in a three-dimensional superconducting vortex-glass phase. The exponent ν derived by this relation coincides with that obtained by nonlinear I-V characteristics for YBa2Cu3Ox films.

The superconducting bridges with constrictions as small as 0.5 µm were fabricated by high-quality Ba2YCu3Ox thin films on silicon with buffer layers. The observed I-V characteristics of this bridge could be successfully analyzed by the modified form of Aslamazov and Larkin theory which shows that our microbridge junction is a homogeneous wide superconducting bridge and the characteristics of this bridge are not dependent on the defects such as grain boundaries of the film.