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Transport électronique dans les nanojonctions supraconducteur - métal normal - supraconducteur

Abstract : In this work, we study the electronic transport in a small isolated metallic grain embedded between two superconducting electrodes. We have developped a new fabricating process to realise niobium-copper-niobium nanojunctions with very transparent interfaces. The critical temperature of niobium is very close to the bulk metal. We first study the DC Josephson effect and present quantitative theoretical and experimental results on the critical current of our junctions. When a voltage is now applied to the junction, the phase difference oscillate at very high frequency. As a result, the electronic distribution function in the metallic island is then pushed out of equilibrium. We mesure a increase of conductance due to electron relaxation via the inelastic scattering process. We also measure the transport when the junction is irradiated with a low powe microwave. The coupling between the microwave and the island induce Shapiro steps when voltage reach V=nhw/2e. At higher temperature the current-voltage characteristics present a lot of fractionary steps. The amplitude of these new steps persist while the Shapiro steps completely disappear. We discuss in term of non-equilibrium contributions of the AC Josephson effect.
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Contributor : Nathalie Le Moulec <>
Submitted on : Thursday, January 22, 2004 - 10:46:54 AM
Last modification on : Friday, December 18, 2020 - 1:34:04 PM
Long-term archiving on: : Friday, April 2, 2010 - 7:25:33 PM


  • HAL Id : tel-00004264, version 1




Pascal Dubos. Transport électronique dans les nanojonctions supraconducteur - métal normal - supraconducteur. Supraconductivité [cond-mat.supr-con]. Université Joseph-Fourier - Grenoble I, 2000. Français. ⟨tel-00004264⟩



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