Temperature dependence of the quantum Hall effect in graphene

We have measured the temperature dependence of the quantum Hall effect in single layer graphene for temperatures ranging from 4 to 300 K in magnetic fields up to 32 T. The gap between higher Landau levels measured at ν=6 follows the classically expected behavior for broadened Landau levels. In contrast, the ν=±2 gap, corresponding to excitations between the zeroth and first Landau level of electrons and holes, behaves totally different and is strongly temperature and field dependent. At high magnetic fields and View the MathML source it approaches the theoretical gap for very sharp Landau levels.