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Superconducting proximity effect in graphene

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Director
Defense Thèse de doctorat : Univ. Genève, 2015 - Sc. 4827 - 2015/09/25
Abstract The experimental results presented in this thesis show how the use of graphene provides new opportunities to investigate unexplored aspects of superconducting proximity effect (SPE). The interplay between decoherence and superconductivity is addressed by investigating the reentrance of SPE in graphene Andreev interferometers. At high gate voltages, the reentrance exhibits a universal scaling which breaks down when the Fermi energy approaches the Dirac point -manifesting how superconducting correlations are limited by single particle dephasing. Further, our spectroscopic study shows how states above the gap (Δ), known as Andreev resonances (AR), contribute to the supercurrent inside Josephson junctions (JJ). The experiment relies on multi-terminal JJ where, in order to investigate the supercurrent at E > Δ, we use graphene as a normal conductor. A considerable supercurrent measured in our junction at E > Δ, when the contribution of subgap states is removed, confirms the importance of AR in the non-dissipative transport.
Keywords GrapheneSuperconductivitySuperconducting Proximity EffectAndreev ReflectionJosephson EffectAndreev InterferometerSupercurrent SpectroscopyReentrance Effect
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URN: urn:nbn:ch:unige-874596
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Research group Groupe Morpurgo
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SOPIC, Sandra. Superconducting proximity effect in graphene. Université de Genève. Thèse, 2015. https://archive-ouverte.unige.ch/unige:87459

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Deposited on : 2016-09-19

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