We have performed magnetotransport measurements on multi-layer epitaxial graphene. By increasing the driving current I through our graphene devices while keeping the bath temperature fixed, we are able to study Dirac fermion heating and current scaling in such devices. Using the zero-field resistivity as a self-thermometer, we are able to determine the effective Dirac fermion temperature TDF at various driving currents. At zero field, it is found that TDF ∝ I ~0.5.Such results are consistent with electron heating in conventional two-dimensional systems in the plateau-plateu transition regime. With increasing magnetic field B, we observe an I-independent point in the measured longitudinal resistivity rxx which is equivalent to the direct insulator-quantum Hall (I-QH) transition characterized by a temperature-independent point in rxx. Together with recent experimental evidence for the direct I-QHtransition, our new data suggests that such a transition is a universal effect in graphene, albeit further studies are required for obtaining a thorough understanding of such an effect.
Citation: Nanoscale Research Letter
Pub Type: Journals
Quantum Hall effect, longitudinal resistivity, Dirac fermion