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Josephson current and multiple Andreev reflections in graphene SNS junctions Xu Du, Ivan Skachko, and Eva Y. Andrei
 

Summary: Josephson current and multiple Andreev reflections in graphene SNS junctions
Xu Du, Ivan Skachko, and Eva Y. Andrei
Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
Received 26 March 2008; published 9 May 2008
The Josephson effect and superconducting proximity effect were observed in superconductor-graphene-
superconductor SGS Josephson junctions with coherence lengths comparable to the distance between the
superconducting leads. By comparing the measured gate dependence of the proximity induced subgap features
multiple Andreev reflections and of the supercurrent to theoretical predictions, we find that the diffusive
junction model yields close quantitative agreement with the results. By contrast, predictions of the ballistic
SGS model are inconsistent with the data. We show that all SGS devices reported so far, our own as well as
those of other groups, fall in the diffusive junction category. This is attributed to substrate induced potential
fluctuations due to trapped charges and to the invasiveness of the metallic leads.
DOI: 10.1103/PhysRevB.77.184507 PACS number s : 74.45. c, 73.50.Gr, 73.63. b, 81.05.Uw
INTRODUCTION
The discovery of methods to extract single atomic layers
from graphite1,2
graphene has triggered a torrential effort to
explore the new physical properties emerging from their rela-
tivistic Dirac quasiparticle spectrum.24 A particularly inter-
esting set of questions and expectations has arisen with the

  

Source: Andrei, Eva Y. - Department of Physics and Astronomy, Rutgers University

 

Collections: Materials Science; Physics