Understanding and Engineering Phonon-Mediated Tunneling into Graphene on Metal Surfaces

Johannes Halle*, Nicolas Néel, Mikhail Fonin, Mads Brandbyge, Jörg Kröger

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Metal-intercalated graphene on Ir(111) exhibits phonon signatures in inelastic electron tunneling spectroscopy with strengths that depend on the intercalant. Extraordinarily strong graphene phonon signals are observed for Cs intercalation. Li intercalation likewise induces clearly discriminable phonon signatures, albeit less pronounced than observed for Cs. The signal can be finely tuned by the alkali metal coverage and gradually disappears upon increasing the junction conductance from tunneling to contact ranges. In contrast to Cs and Li, for Ni-intercalated graphene the phonon signals stay below the detection limit in all transport ranges. Going beyond the conventional two-terminal approach, transport calculations provide a comprehensive understanding of the subtle interplay between the graphene–electrode coupling and the observation of graphene phonon spectroscopic signatures.
Original languageEnglish
JournalNano letters
Issue number9
Pages (from-to)5697-5701
Number of pages5
Publication statusPublished - 2018


  • Scanning tunneling microscopy
  • Inelastic electron tunneling spectroscopy
  • Graphene
  • Intercalation
  • Density functional theory
  • Nonequilibrium Green function


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