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Screening Charged Impurities and Lifting the Orbital Degeneracy in Graphene by Populating Landau Levels

Adina Luican-Mayer, Maxim Kharitonov, Guohong Li, Chih-Pin Lu, Ivan Skachko, Alem-Mar B. Gonçalves, K. Watanabe, T. Taniguchi, and Eva Y. Andrei
Phys. Rev. Lett. 112, 036804 – Published 23 January 2014

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.

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  • Received 19 July 2013

DOI:https://doi.org/10.1103/PhysRevLett.112.036804

© 2014 American Physical Society

Authors & Affiliations

Adina Luican-Mayer1, Maxim Kharitonov1, Guohong Li1, Chih-Pin Lu1, Ivan Skachko1, Alem-Mar B. Gonçalves1, K. Watanabe2, T. Taniguchi2, and Eva Y. Andrei1,*

  • 1Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
  • 2Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan

  • *Corresponding author. eandrei@physics.rutgers.edu

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Vol. 112, Iss. 3 — 24 January 2014

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