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Unconventional quantum Hall effect and Berry’s phase 2pi in bilayer graphene.

Novoselov, K. S. and McCann, Edward and Morozov, S. V. and Fal’ko, Vladimir I. and Katsnelson, M. I. and Zeitler, U. and Jiang, D. and Schedin, F. and Geim, A. K. (2006) Unconventional quantum Hall effect and Berry’s phase 2pi in bilayer graphene. Nature Physics, 2 (3). pp. 177-180. ISSN 1745-2473

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    Abstract

    There are known two distinct types of the integer quantum Hall effect. One is the conventional quantum Hall effect, characteristic of two-dimensional semiconductor systems, and the other is its relativistic counterpart recently observed in graphene, where charge carriers mimic Dirac fermions characterized by Berry’s phase pi, which results in a shifted positions of Hall plateaus. Here we report a third type of the integer quantum Hall effect. Charge carriers in bilayer graphene have a parabolic energy spectrum but are chiral and exhibit Berry’s phase 2pi affecting their quantum dynamics. The Landau quantization of these fermions results in plateaus in Hall conductivity at standard integer positions but the last (zero-level) plateau is missing. The zero-level anomaly is accompanied by metallic conductivity in the limit of low concentrations and high magnetic fields, in stark contrast to the conventional, insulating behavior in this regime. The revealed chiral fermions have no known analogues and present an intriguing case for quantum-mechanical studies.

    Item Type: Article
    Journal or Publication Title: Nature Physics
    Subjects: Q Science > QC Physics
    Departments: Faculty of Science and Technology > Physics
    ID Code: 30826
    Deposited By: Dr Edward McCann
    Deposited On: 08 Dec 2009 09:22
    Refereed?: Yes
    Published?: Published
    Last Modified: 26 Jul 2012 16:50
    Identification Number:
    URI: http://eprints.lancs.ac.uk/id/eprint/30826

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