Coherent low-energy charge transport in a diffusive S-N-S junction.
We have studied the current-voltage characteristics of diffusive mesoscopic Nb-Cu-Nb Josephson junctions with highly transparent Nb-Cu interfaces. We consider the low-voltage and high-temperature regime eV < epsilon(c) < k(B)T, where epsilon(c) is the Thouless energy. The observed excess current as well as the observed subharmonic Shapiro steps under microwave irradiation suggest the occurrence of low-energy coherent multiple Andreev reflection.
Dubos
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Centre de Recherches sur les Très Basses Températures, C.N.R.S., associé à l'Université Joseph Fourier, 25 Av. des Martyrs, 38042 Grenoble, France.
Courtois
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Buisson
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Pannetier
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