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Andreev reflection in ballistic normal metal/graphene/superconductor junctions

Pandey, P. and Kraft, R. and Krupke, R. and Beckmann, D. and Danneau, R. (2019):
Andreev reflection in ballistic normal metal/graphene/superconductor junctions.
In: Physical Review B, 100 (16), p. 165416. American Physical Society, ISSN 2469-9950,
DOI: 10.1103/PhysRevB.100.165416,
[Article]

Abstract

We report the study of ballistic transport in normal metal/graphene/superconductor junctions in edge-contactgeometry. While in the normal state, we have observed Fabry-Pérot resonances suggesting that charge carrierstravel ballistically, the superconducting state shows that the Andreev reflection at the graphene/superconductorinterface is affected by these interferences. Our experimental results in the superconducting state have beenanalyzed and explained with a modified Octavio-Tinkham-Blonder-Klapwijk model taking into account themagnetic pair-breaking effects and the two different interface transparencies,i.e.between the normal metaland graphene, and between graphene and the superconductor. We show that the transparency of the normalmetal/graphene interface strongly varies with doping at large scale, while it undergoes weaker changes at thegraphene/superconductor interface. When a cavity is formed by the charge transfer occurring in the vicinityof the contacts, we see that the transmission probabilities follow the normal state conductance highlighting theinterplay between the Andreev processes and the electronic interferometer.

Item Type: Article
Erschienen: 2019
Creators: Pandey, P. and Kraft, R. and Krupke, R. and Beckmann, D. and Danneau, R.
Title: Andreev reflection in ballistic normal metal/graphene/superconductor junctions
Language: English
Abstract:

We report the study of ballistic transport in normal metal/graphene/superconductor junctions in edge-contactgeometry. While in the normal state, we have observed Fabry-Pérot resonances suggesting that charge carrierstravel ballistically, the superconducting state shows that the Andreev reflection at the graphene/superconductorinterface is affected by these interferences. Our experimental results in the superconducting state have beenanalyzed and explained with a modified Octavio-Tinkham-Blonder-Klapwijk model taking into account themagnetic pair-breaking effects and the two different interface transparencies,i.e.between the normal metaland graphene, and between graphene and the superconductor. We show that the transparency of the normalmetal/graphene interface strongly varies with doping at large scale, while it undergoes weaker changes at thegraphene/superconductor interface. When a cavity is formed by the charge transfer occurring in the vicinityof the contacts, we see that the transmission probabilities follow the normal state conductance highlighting theinterplay between the Andreev processes and the electronic interferometer.

Journal or Publication Title: Physical Review B
Journal volume: 100
Number: 16
Publisher: American Physical Society
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Fachgebiet Molekulare Nanostrukturen
Date Deposited: 20 Nov 2020 11:58
DOI: 10.1103/PhysRevB.100.165416
Official URL: https://journals.aps.org/prb/abstract/10.1103/PhysRevB.100.1...
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