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Overdoping Graphene beyond the van Hove Singularity

Philipp Rosenzweig, Hrag Karakachian, Dmitry Marchenko, Kathrin Küster, and Ulrich Starke
Phys. Rev. Lett. 125, 176403 – Published 19 October 2020
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Abstract

At very high doping levels the van Hove singularity in the π* band of graphene becomes occupied and exotic ground states possibly emerge, driven by many-body interactions. Employing a combination of ytterbium intercalation and potassium adsorption, we n dope epitaxial graphene on silicon carbide past the π* van Hove singularity, up to a charge carrier density of 5.5×1014cm2. This regime marks the unambiguous completion of a Lifshitz transition in which the Fermi surface topology has evolved from two electron pockets into a giant hole pocket. Angle-resolved photoelectron spectroscopy confirms these changes to be driven by electronic structure renormalizations rather than a rigid band shift. Our results open up the previously unreachable beyond-van-Hove regime in the phase diagram of epitaxial graphene, thereby accessing an unexplored landscape of potential exotic phases in this prototype two-dimensional material.

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  • Received 14 July 2020
  • Accepted 9 September 2020

DOI:https://doi.org/10.1103/PhysRevLett.125.176403

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Open access publication funded by the Max Planck Society.

Published by the American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

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Graphene Doping Reaches New Levels

Published 19 October 2020

New experiments with doped graphene take the two-dimensional material beyond its “Van Hove singularity” to regions that may host exotic states of matter.

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Authors & Affiliations

Philipp Rosenzweig1,*, Hrag Karakachian1, Dmitry Marchenko2, Kathrin Küster1, and Ulrich Starke1

  • 1Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
  • 2Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany

  • *p.rosenzweig@fkf.mpg.de

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Vol. 125, Iss. 17 — 23 October 2020

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