Hopping conductivity in the quantum Hall effect: Revival of universal scaling

The temperature and electric field dependence of the conductivity in the quantum Hall effect (QHE) plateau transition for samples where no universal behavior is found in the conventional temperature dependent peak-width scaling experiments was examined. A revival of universality in the variable-range hopping (VRH) regime was found. Furthermore, it was possible to rescale all the data on the Landau gap side of the transition on a single parameter function over more than 5 orders of magnitude in the conductivity