title: Real-space imaging of alternate localization and extension of quasi-two-dimensional electronic States at graphite surfaces in magnetic fields.
abstract: We measured the local density of states (LDOS) of a quasi-two-dimensional (2D) electron system near point defects on a surface of highly oriented pyrolytic graphite with scanning tunneling microscopy and spectroscopy. Differential tunnel conductance images taken at very low temperatures and in high magnetic fields show a clear contrast between localized and extended spatial distributions of the LDOS at the valley and peak energies of the Landau level spectrum, respectively. The localized electronic state has a single circular distribution around the defects with a radius comparable to the magnetic length. The localized LDOS is in good agreement with a spatial distribution of a calculated wave function for a single electron in 2D in a Coulomb potential in magnetic fields.
authors.affiliation: Department of Physics, University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Niimi
authors.forename: H
authors.initials: H
authors.lastname: Kambara
authors.forename: T
authors.initials: T
authors.lastname: Matsui
authors.forename: D
authors.initials: D
authors.lastname: Yoshioka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Fukuyama