Resonance Raman Spectrum of Doped Epitaxial Graphene at the Lifshitz Transition

Martin G. Hell, Niels Ehlen, Boris V. Senkovskiy, Eddwi H. Hasdeo, Alexander Fedorov, Daniela Dombrowski, Carsten Busse, Thomas Michely, Giovanni Di Santo, Luca Petaccia, Riichiro Saito, Alexander Grüneis

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

We employ ultra-high vacuum (UHV) Raman spectroscopy in tandem with angle-resolved photoemission (ARPES) to investigate the doping-dependent Raman spectrum of epitaxial graphene on Ir(111). The evolution of Raman spectra from pristine to heavily Cs doped graphene up to a carrier concentration of 4.4 × 1014 cm-2 is investigated. At this doping, graphene is at the onset of the Lifshitz transition and renormalization effects reduce the electronic bandwidth. The optical transition at the saddle point in the Brillouin zone then becomes experimentally accessible by ultraviolet (UV) light excitation, which achieves resonance Raman conditions in close vicinity to the van Hove singularity in the joint density of states. The position of the Raman G band of fully doped graphene/Ir(111) shifts down by ∼60 cm-1. The G band asymmetry of Cs doped epitaxial graphene assumes an unusual strong Fano asymmetry opposite to that of the G band of doped graphene on insulators. Our calculations can fully explain these observations by substrate dependent quantum interference effects in the scattering pathways for vibrational and electronic Raman scattering.

Original languageEnglish
Pages (from-to)6045-6056
Number of pages12
JournalNano Letters
Volume18
Issue number9
DOIs
Publication statusPublished - 2018 Sep 12

Keywords

  • ARPES
  • Alkali doping
  • Lifshitz
  • UHV Raman
  • graphene

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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  • Cite this

    Hell, M. G., Ehlen, N., Senkovskiy, B. V., Hasdeo, E. H., Fedorov, A., Dombrowski, D., Busse, C., Michely, T., Di Santo, G., Petaccia, L., Saito, R., & Grüneis, A. (2018). Resonance Raman Spectrum of Doped Epitaxial Graphene at the Lifshitz Transition. Nano Letters, 18(9), 6045-6056. https://doi.org/10.1021/acs.nanolett.8b02979