Real-space imaging of alternate localization and extension of quasi-two-dimensional electronic States at graphite surfaces in magnetic fields.
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.
Niimi
Y
Y
Department of Physics, University of Tokyo, Tokyo 113-0033, Japan.
Kambara
H
H
Matsui
T
T
Yoshioka
D
D
Fukuyama
Hiroshi
H