Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 41: Graphene: Growth, Substrate Interaction, Intercalation, and Doping
O 41.8: Vortrag
Mittwoch, 7. September 2022, 12:15–12:30, S052
Electron correlation effects in highly-doped single-layer graphene — •Vivien Enenkel1, Philipp Rosenzweig2, Hrag Karakachian2, Fabian Paschke1, Ulrich Starke2, and Mikhail Fonin1 — 1Fachbereich Physik, Universität Konstanz, 78457 Konstanz, Germany — 2Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
Electronic correlations in graphene are expected to be strongly enhanced when there is a very high density of states at the Fermi level, giving rise to many-body states such as superconductivity or charge density waves (CDW) [1]. While the latter have been reported for example in Ca-intercalated bilayer graphene [2,3], in case of epitaxial monolayer graphene no direct evidence of correlated electronic ground states has yet been reported. We investigate heavily n-doped monolayer graphene on SiC(0001), obtained by Yb intercalation underneath zero-layer graphene. Here, a van Hove singularity (VHS) is pushed to the Fermi level, giving rise to an extended VHS, effectively pinning an almost non-dispersive flat band at EF [4]. Low-temperature STM reveals several distinct structures of Yb-intercalated graphene, which we attribute to differing arrangements of the Yb at the interface. dI/dU spectra show a pronounced gap feature centered at EF, whose response to field and temperature variations allows the interpretation of the feature as a CDW state. [1] M. L. Kiesel et al., Phys. Rev. B 86, 020507 (2012); [2] R. Shimizu et al., Phys. Rev. Lett., 114, 146103 (2015); [3] S. Ichinokura et al., ACS Nano 10, 2, 2761 (2016); [4] P. Rosenzweig et al., Phys. Rev. B 100, 035445 (2019).