title: How close can one approach the Dirac point in graphene experimentally?
abstract: The above question is frequently asked by theorists who are interested in graphene as a model system, especially in context of relativistic quantum physics. We offer an experimental answer by describing electron transport in suspended devices with carrier mobilities of several 10(6) cm(2) V(-1) s(-1) and with the onset of Landau quantization occurring in fields below 5 mT. The observed charge inhomogeneity is as low as ≈10(8) cm(-2), allowing a neutral state with a few charge carriers per entire micrometer-scale device. Above liquid helium temperatures, the electronic properties of such devices are intrinsic, being governed by thermal excitations only. This yields that the Dirac point can be approached within 1 meV, a limit currently set by the remaining charge inhomogeneity. No sign of an insulating state is observed down to 1 K, which establishes the upper limit on a possible bandgap.
authors.affiliation: School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom. mayorov@gmail.com
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Mayorov
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Elias
authors.forename: Ivan S
authors.initials: IS
authors.lastname: Mukhin
authors.forename: Sergey V
authors.initials: SV
authors.lastname: Morozov
authors.forename: Leonid A
authors.initials: LA
authors.lastname: Ponomarenko
authors.forename: Kostya S
authors.initials: KS
authors.lastname: Novoselov
authors.forename: A K
authors.initials: AK
authors.lastname: Geim
authors.forename: Roman V
authors.initials: RV
authors.lastname: Gorbachev
mesh_terms: D003198:Computer Simulation; D004579:Electron Transport; D006108:Graphite / Q000737:chemistry*; D008956:Models, Chemical; D055672:Static Electricity
chemical_list: D006108:Graphite