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 5.5×10^{14} cm^{-2}. 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.
Highlights
At very high doping levels the van Hove singularity in the πà 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 πà van Hove singularity, up to a charge carrier density of 5.5 × 1014 cm−2. 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
Summary
Philipp Rosenzweig ,1,* Hrag Karakachian ,1 Dmitry Marchenko ,2 Kathrin Küster ,1 and Ulrich Starke 1 At very high doping levels the van Hove singularity in the πà band of graphene becomes occupied and exotic ground states possibly emerge, driven by many-body interactions.
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