1202.1690 (Katsuyoshi Komatsu et al.)

Superconducting proximity effect through graphene from zero field to the
Quantum Hall regime    [PDF]

Katsuyoshi Komatsu, Chuan Li, S. Autier-Laurent, H. Bouchiat, S. Gueron

We investigate the superconducting proximity effect through graphene in the
long diffusive junction limit, at low and high magnetic field. The interface
quality and sample phase coherence lead to a zero resistance state at low
temperature, zero magnetic field, and high doping. We find a striking
suppression of the critical current near graphene\rq{}s charge neutrality
point, which we attribute to specular reflexion of Andreev pairs at the
interface of charge puddles. This type of reflexion, specific to the Dirac band
structure, had up to now remained elusive. At high magnetic field the use of
superconducting electrodes with high critical field enables the investigation
of the proximity effect in the Quantum Hall regime. Although the supercurrent
is not directly detectable in our two wire configuration, interference effects
are visible which may be attributed to the injection of Cooper pairs into edge
states.

View original: http://arxiv.org/abs/1202.1690