title: Collapse of Landau levels in gated graphene structures.
abstract: We describe a new regime of magnetotransport in two-dimensional electron systems in the presence of a narrow potential barrier. In such systems, the Landau level states, which are confined to the barrier region in strong magnetic fields, undergo a deconfinement transition as the field is lowered. Transport measurements on a top-gated graphene device are presented. Shubnikov-de Haas (SdH) oscillations, observed in the unipolar regime, are found to abruptly disappear when the strength of the magnetic field is reduced below a certain critical value. This behavior is explained by a semiclassical analysis of the transformation of closed cyclotron orbits into open, deconfined trajectories.
authors.affiliation: Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, Massachusetts 02139, USA.
authors.forename: Nan
authors.initials: N
authors.lastname: Gu
authors.forename: Mark
authors.initials: M
authors.lastname: Rudner
authors.forename: Andrea
authors.initials: A
authors.lastname: Young
authors.forename: Philip
authors.initials: P
authors.lastname: Kim
authors.forename: Leonid
authors.initials: L
authors.lastname: Levitov
mesh_terms: D017357:Cyclotrons; D004560:Electricity; D006108:Graphite / Q000737:chemistry*; D008280:Magnetics; D009038:Motion
chemical_list: D006108:Graphite