  The conductance of graphene subject to a strong, tilted magnetic field
exhibits a dramatic change from insulating to conducting behavior with
tilt-angle, regarded as evidence for the transition from a canted
antiferromagnetic (CAF) to a ferromagnetic (FM) \nu=0 quantum Hall state. We
develop a theory for the electric transport in this system based on the
spin-charge connection, whereby the evolution in the nature of collective spin
excitations is reflected in the charge-carrying modes. To this end, we derive
an effective field theoretical description of the low-energy excitations,
associated with quantum fluctuations of the spin-valley domain wall
ground-state configuration which characterizes the two-dimensional (2D) system
with an edge. This analysis yields a model describing a one-dimensional charged
edge mode coupled to charge-neutral spin-wave excitations in the 2D bulk.
Focusing particularly on the FM phase, naively expected to exhibit perfect
conductance, we study a mechanism whereby the coupling to these bulk
excitations assists in generating back-scattering. Our theory yields the
conductance as a function of temperature and the Zeeman energy - the parameter
that tunes the transition between the FM and CAF phases - with behavior in
qualitative agreement with experiment.
