Universal distribution of transparencies in highly conductive Nb/AlO${}_x$/Nb junctions

Abstract

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.

4 pages, 4 figures, references added

References in corpus (3)

• Random-Matrix Theory of Quantum Transport
• Coherent effects in double-barrier Josephson junctions
• Universality of Shot-Noise in Multiterminal Diffusive Conductors

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