Graphene -a recently discovered one-atom-thick layer of graphite- constitutes
a new model system in condensed matter physics, because it is the first
material in which charge carriers behave as massless chiral relativistic
particles. The anomalous quantization of the Hall conductance, which is now
understood theoretically, is one of the experimental signatures of the peculiar
transport properties of relativistic electrons in graphene. Other unusual
phenomena, like the finite conductivity of order 4e^2/h at the charge
neutrality (or Dirac) point, have come as a surprise and remain to be
explained. Here, we study the Josephson effect in graphene. Our experiments
rely on mesoscopic superconducting junctions consisting of a graphene layer
contacted by two closely spaced superconducting electrodes, where the charge
density can be controlled by means of a gate electrode. We observe a
supercurrent that, depending on the gate voltage, is carried by either
electrons in the conduction band or by holes in the valence band. More
importantly, we find that not only the normal state conductance of graphene is
finite, but also a finite supercurrent can flow at zero charge density. Our
observations shed light on the special role of time reversal symmetry in
graphene and constitute the first demonstration of phase coherent electronic
transport at the Dirac point.
%0 Generic
%1 Heersche2006Bipolar
%A Heersche, Hubert B.
%A Jarillo-Herrero, Pablo
%A Oostinga, Jeroen B.
%A Vandersypen, Lieven M. K.
%A Morpurgo, Alberto F.
%D 2006
%K graphene
%T Bipolar supercurrent in graphene
%U http://arxiv.org/abs/cond-mat/0612121
%X Graphene -a recently discovered one-atom-thick layer of graphite- constitutes
a new model system in condensed matter physics, because it is the first
material in which charge carriers behave as massless chiral relativistic
particles. The anomalous quantization of the Hall conductance, which is now
understood theoretically, is one of the experimental signatures of the peculiar
transport properties of relativistic electrons in graphene. Other unusual
phenomena, like the finite conductivity of order 4e^2/h at the charge
neutrality (or Dirac) point, have come as a surprise and remain to be
explained. Here, we study the Josephson effect in graphene. Our experiments
rely on mesoscopic superconducting junctions consisting of a graphene layer
contacted by two closely spaced superconducting electrodes, where the charge
density can be controlled by means of a gate electrode. We observe a
supercurrent that, depending on the gate voltage, is carried by either
electrons in the conduction band or by holes in the valence band. More
importantly, we find that not only the normal state conductance of graphene is
finite, but also a finite supercurrent can flow at zero charge density. Our
observations shed light on the special role of time reversal symmetry in
graphene and constitute the first demonstration of phase coherent electronic
transport at the Dirac point.
@electronic{Heersche2006Bipolar,
abstract = {{Graphene -a recently discovered one-atom-thick layer of graphite- constitutes
a new model system in condensed matter physics, because it is the first
material in which charge carriers behave as massless chiral relativistic
particles. The anomalous quantization of the Hall conductance, which is now
understood theoretically, is one of the experimental signatures of the peculiar
transport properties of relativistic electrons in graphene. Other unusual
phenomena, like the finite conductivity of order 4e^2/h at the charge
neutrality (or Dirac) point, have come as a surprise and remain to be
explained. Here, we study the Josephson effect in graphene. Our experiments
rely on mesoscopic superconducting junctions consisting of a graphene layer
contacted by two closely spaced superconducting electrodes, where the charge
density can be controlled by means of a gate electrode. We observe a
supercurrent that, depending on the gate voltage, is carried by either
electrons in the conduction band or by holes in the valence band. More
importantly, we find that not only the normal state conductance of graphene is
finite, but also a finite supercurrent can flow at zero charge density. Our
observations shed light on the special role of time reversal symmetry in
graphene and constitute the first demonstration of phase coherent electronic
transport at the Dirac point.}},
added-at = {2019-02-26T15:22:34.000+0100},
archiveprefix = {arXiv},
author = {Heersche, Hubert B. and Jarillo-Herrero, Pablo and Oostinga, Jeroen B. and Vandersypen, Lieven M. K. and Morpurgo, Alberto F.},
biburl = {https://www.bibsonomy.org/bibtex/254c86655f9ad4cc07721046f00f81c1f/rspreeuw},
citeulike-article-id = {976943},
citeulike-linkout-0 = {http://arxiv.org/abs/cond-mat/0612121},
citeulike-linkout-1 = {http://arxiv.org/pdf/cond-mat/0612121},
day = 5,
eprint = {cond-mat/0612121},
interhash = {70d42cc6523954afbdb42b688c7c8041},
intrahash = {54c86655f9ad4cc07721046f00f81c1f},
keywords = {graphene},
month = dec,
posted-at = {2007-03-10 21:29:36},
priority = {2},
timestamp = {2019-02-26T15:22:34.000+0100},
title = {{Bipolar supercurrent in graphene}},
url = {http://arxiv.org/abs/cond-mat/0612121},
year = 2006
}