We report the observation of the universal distribution of transparencies, predicted by Schep and Bauer [Phys. Rev. Lett. { \bf 78}, 3015 (1997)] for dirty sharp interfaces, in uniform Nb/AlO$_x$/Nb junctions with high specific conductance ($10^8$ Ohm$^{ -1}$cm$^{ -2}$). Experiments used the BCS density of states in superconducting niobium for transparency distribution probing. Experimental results for both the dc $I-V$ curves at magnetic-field-suppressed supercurrent and the Josephson critical current in zero magnetic field coincide remarkably well with calculations based on the multimode theory of multiple Andreev reflections and the Schep-Bauer distribution.
Categories: cond-mat.mes-hall cond-mat.supr-con
