Emiliano Pallecchi
In this talk I will present magneto-transport measurements on epitaxial graphene grown on SiC(0001), either under UHV or atmospheric pressure. A low pressure growth results in lowmobility devices were both a localized state at low magnetic fields and a quantum Hall state at higher fields are observed. We find that for sufficiently strong disorder the system undergoes a direct transition from an insulating to a relativistic Hall conductor regime. Analysis of the magneto-conductivity hints to a quantum phase transitions, rather than a simple crossover. For samples grown at atmospheric pressure we find high mobilities, up to 10.000 cm2/Vs, and the plateau at nu=2,6,10,14. Given the large sizes of our graphene Hall bars, the quantum Hall breakdown current are large, as required for metrological applications. Finally, I will briefly discuss the case of multi-layer graphene grown on SiC(000-1).
E. Pallecch (i1), M. Ridene (1), D. Kazazis (1), F. Schopfer (2), W. Poirier (2), M. Goerbig (3), D. Mailly (1), and A. Ouerghi (1)
1) CNRS - Laboratoire de Photonique et de Nanostructures, 91460 Marcoussis, France
2) Laboratoire National de Metrologie et d’Essais, 78197 Trappes, France
3) Laboratoire des Physique de Solides, F-91505, Orsay, France