Electron-phonon coupling origin of the graphene 
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-band kink via isotope effect

Bisti, F.; Priante, F.; Fedorov, Alexander; Donarelli, M.; Fantasia, M.; Petaccia, L.; Frank, Otakar; Kalbáč, Martin; Profeta, G.; Grüneis, A.; Ottaviano, L.

doi:10.1103/physrevb.103.035119

Cited by 5 publications

(5 citation statements)

References 37 publications

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“…S2(g) of the Supplementary Material and related discussion [34]), considering that, for the purpose of this analysis the overall doping is not so relevant. Interestingly, we notice an unexpected significant energy shift of the kink with respect to the value of highly doped system with Li (-169 meV) [31], which is now centered at -147 meV, representing the charac- teristic E 2g phonon frequency. This shift is even larger than that observed in a graphene completely substituted with 13 C (-162 meV) [31] and cannot be explained by an artificial error due to data manipulation.…”

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confidence: 82%

“…Interestingly, we notice an unexpected significant energy shift of the kink with respect to the value of highly doped system with Li (-169 meV) [31], which is now centered at -147 meV, representing the charac- teristic E 2g phonon frequency. This shift is even larger than that observed in a graphene completely substituted with 13 C (-162 meV) [31] and cannot be explained by an artificial error due to data manipulation. The observed softening of the phonon modes is a natural consequence of the effect of Li decoration on both sides of graphene and of the increased doping level: indeed first-principles theoretical calculations of phonon dispersion for a graphene layer decorated on both sides, have correctly predicted this softening (see Supplementary Material of Ref.…”

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confidence: 82%

“…Recent band structure measurement of doped graphene have detected relevant deviations from a simple rigid shift of neutral graphene or of the first-principles density functional theory (DFT) band structure. Apart from the general consensus on the band renormalization around 170 meV due to the electron-phonon interaction [31], a strong flattening of the band close to E F has been interpreted as originating from electron-electron correlations due to onsite Coulomb interaction U [22] or spin fluctuations [27]. However, the interpretation of the experimental results are complicated by the graphene's band hybridization with dopant atoms and/or intercalant atoms deposited on the substrate.…”

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confidence: 99%

“…4 we report the kink analysis for the present system, using the same computational analysis as in Ref. [31]. In this case, in order to reduce the "shadow" signal near the Fermi energy (which can interfere with the fitting procedure), we used a slightly under-doped (2.5 × 10 14 /cm 2 ) system with respect the data shown before (see Fig.…”

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confidence: 99%

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Can the "shadow" of graphene band clarify its flatness?

Jugovac,

Tresca,

Cojocariu

et al. 2022

Preprint

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Graphene band renormalization at the proximity of the van Hove singularity (VHS) has been investigated by angle-resolved photoemission spectroscopy (ARPES) on the Li-doped quasi-freestanding graphene on the cobalt (0001) surface. The absence of graphene band hybridization with the substrate, the doping contribution well represented by a rigid energy shift and the excellent electronelectron interaction screening ensured by the metallic substrate offer a privileged point of view for such investigation. A clear ARPES signal is detected along the M point of the graphene Brillouin zone, giving rise to an apparent flattened band. By simulating the graphene spectral function from the density functional theory calculated bands, we demonstrate that the photoemission signal along the M point originates from the "shadow" of the spectral function of the unoccupied band above the Fermi level. Such interpretation put forward the absence of any additional strong correlation effects at the VHS proximity, reconciling the mean field description of the graphene band structure even in the highly doped scenario.

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confidence: 82%

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confidence: 82%

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confidence: 99%

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confidence: 99%

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Can the "shadow" of graphene band clarify its flatness?

Jugovac,

Tresca,

Cojocariu

et al. 2022

Preprint

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“…Figs. 2(a) and (c)] that has been studied extensively for different (intercalated) graphene systems [45][46][47]67 . Fig.…”

Section: Tunable Many-body Interactions In Graphenementioning

confidence: 99%

Tuning a quantum-confined silver monolayer beneath epitaxial graphene via surface charge-transfer doping

Rosenzweig,

Karakachian,

Marchenko

et al. 2022

Preprint

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Recently the graphene/SiC interface has emerged as a versatile platform for the epitaxy of otherwise unstable, monoelemental, two-dimensional (2D) layers via intercalation. Intrinsically capped into a van der Waals heterostructure with overhead graphene, they compose a new class of quantum materials with striking properties contrasting their parent bulk crystals. Intercalated silver presents a prototypical example where 2D quantum confinement and inversion symmetry breaking entail a metal-to-semiconductor transition. However, little is known about the associated unoccupied states and coherent control of the Fermi level position across the bandgap would be desirable. Here, we n-type dope a graphene/2D-Ag/SiC heterostack via in situ potassium deposition and probe its band structure by means of synchrotron-based angle-resolved photoelectron spectroscopy. While the induced carrier densities on the order of 10 14 cm −2 are not yet sufficient to reach the onset of the silver conduction band, the band alignment of graphene can be tuned relative to the rigidly shifting Ag valence band and substrate core levels. We further demonstrate an ordered potassium adlayer (2 × 2 relative to graphene) with free-electron-like dispersion, suppressing plasmaron quasiparticles in graphene via enhanced metalization of the heterostack. Our results establish surface charge-transfer doping as an efficient handle to tune band alignment and electronic properties of a van der Waals heterostructure assembled from graphene and a novel type of monolayered quantum material.

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