1. Screening Charged Impurities and Lifting the Orbital Degeneracy in Graphene by Populating Landau Levels
- Author
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Luican-Mayer, Adina, Kharitonov, Maxim, Li, Guohong, Lu, 1 ChihPin, Skachko, Ivan, Goncalves, Alem-Mar B., Watanabe, K., Taniguchi, T., and Andrei, Eva Y.
- Subjects
Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
We report the observation of an isolated charged impurity in graphene and present direct evidence of the close connection between the screening properties of a 2D electron system and the influence of the impurity on its electronic environment. Using scanning tunneling microscopy and Landau level spectroscopy we demonstrate that in the presence of a magnetic field the strength of the impurity can be tuned by controlling the occupation of Landau-level states with a gate-voltage. At low occupation the impurity is screened becoming essentially invisible. Screening diminishes as states are filled until, for fully occupied Landau-levels, the unscreened impurity significantly perturbs the spectrum in its vicinity. In this regime we report the first observation of Landau-level splitting into discrete states due to lifting the orbital degeneracy., Comment: 13 pages, 4 figures
- Published
- 2013
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