  The quantum Hall regime of graphene has many unusual properties. In
particular, the presence of a Zeeman field opens up a region of energy within
the zeroth Landau level, where the spin-up and spin-down states localized at a
single edge propagate in opposite directions. We show that when these edge
states are coupled to an s-wave superconductor, the transport of charge
carriers is spin-filtered. This spin-filtering effect can be traced back to the
interplay of specular Andreev reflections and Andreev retro-reflections in the
presence of a Zeeman field.
