  The quantum localization in the quantum Hall regime is revisited using
Graphene monolayers with accurate measurements of the longitudinal resistivity
as a function of temperature and current. We experimentally show for the first
time a cross-over from Efros-Shklovskii Variable Range Hopping (VRH) conduction
regime with Coulomb interactions to a Mott VRH regime without interaction. This
occurs at Hall plateau transitions for localization lengths larger than the
interaction screening length set by the nearby gate. Measurements of the
scaling exponents of the conductance peak widths with both temperature and
current give the first validation of the Polyakov-Shklovskii scenario that VRH
alone is sufficient to describe conductance in the Quantum Hall regime and that
the usual assumption of a metallic conduction regime on conductance peaks is
unnecessary.
