Current-phase relation in graphene and application to a superconducting quantum interference device

Graphene exhibits unique electrical properties on account of its reduced dimensionality and neutrino-like massless Dirac fermion quasiparticle spectrum. When contacted with two superconducting electrodes, graphene can support Cooper pair transport, resulting in the well-known Josephson effect. The current-phase relation in a ballistic graphene Josephson junction is unique, and could provide a signature for the detection of ballistic Dirac fermions. This relation can be measured experimentally either directly via incorporation of graphene in an RF superconducting quantum interference device (SQUID) or indirectly via a dc-SQUID. We calculate the [GRAPHICS] expected flux modulation of the switching current in the case of the dc-SQUID and compare the results to a previous experiment. Further experiments investigating the current-phase relation in graphene are promising for the observation of ballistic Dirac fermions. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim