Effect of moiré superlattice reconstruction in the electronic excitation spectrum of graphene-metal heterostructures

Politano, Antonio; Slotman, Guus J.; Roldán, Rafael; Chiarello, G.; Campi, Davide; Katsnelson, M. I.; Yuan, Shengjun

doi:10.1088/2053-1583/aa53ba

Cited by 13 publications

(12 citation statements)

References 46 publications

(91 reference statements)

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“…The answer seems to be that maximum vertical confinement can be achieved by depositing graphene directly on the metal gate. (Note that here we are not interested in the case of samples where graphene is grown by chemical vapour deposition on selected metals [15][16][17][18][19][20][21][22][23]. Often, in this case, hybridization occurs between graphene and metal bands, leading to plasmonic excitations that share very little with graphene plasmons and that are usually accompanied by strong damping.)…”

mentioning

confidence: 99%

Confining graphene plasmons to the ultimate limit

Principi

Loon²,

Polini

et al. 2018

Phys. Rev. B

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Graphene plasmons have recently attracted a great deal of attention because of their tunability, long lifetime, and high degree of field confinement in the vertical direction. Nearby metal gates have been shown to modify the graphene plasmon dispersion and further confine their electric field. We study the plasmons of a graphene sheet deposited on a metal, in the regime in which metal bands do not hybridize with massless Dirac fermion bands. We derive exact results for the dispersion and lifetime of the plasmons of such hybrid system, taking into account metal nonlocalities. The graphene plasmon dispersion is found to be acoustic and pushed down in energy towards the upper boundary of the intraband graphene particle-hole continuum, thereby strongly enhancing the vertical confinement of these excitations. Landau damping of such acoustic plasmons due to particle-hole excitations in the metal gate is found to be surprisingly weak, with quality factors exceeding Q = 10 2 .Introduction.-Recently, the fundamental properties of graphene plasmons and hybrid plasmon-phonon polaritons in graphene encapsulated in hexagonal boron nitride (hBN) have been studied in an extensive manner [1][2][3]. In encapsulated graphene, plasmons have record-high lifetimes approaching 1 ps both in the mid-infrared [4] and Terahertz (THz) [5,6] spectral ranges, while at the same time displaying strong vertical confinement.The plasmon dispersion relation in graphene can be engineered not only by coupling them to standing Fabry-Pérot phonon polariton modes of hBN slabs [7], but also by placing metal gates nearby. These have been shown to play two vital roles. On the one hand, when shaped in the form of split gates, the associated p-n junctions allow to detect plasmons electrically thanks to the photothermoelectric effect [8]. On the other hand, they screen the long-range tail of the electron-electron interaction potential, yielding acoustic plasmon modes [9-11] whose associated electric field is tightly confined to the small volume between the metal gate and graphene [5]. The latter is typically filled with an hBN spacer, which can be thinned down to a single layer or even removed. The modification of the plasmon dispersion from the usual unscreened √ q

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mentioning

confidence: 99%

Confining graphene plasmons to the ultimate limit

Principi

Loon²,

Polini

et al. 2018

Phys. Rev. B

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“…The corrugation of gr/Ru(0001) was noted already in earlier studies, , and it has been shown that its moiré structure can serve as a template for the growth of well-ordered lattices of metal nanoclusters and organic molecules . Furthermore, the electronic structure of graphene is strongly perturbed as compared to free-standing graphene, − and the corrugation leads to special, localized phonon modes , and plasmon modes. , …”

Section: Introductionmentioning

confidence: 75%

“…7 Furthermore, the electronic structure of graphene is strongly perturbed as compared to free-standing graphene, 8−10 and the corrugation leads to special, localized phonon modes 11,12 and plasmon modes. 13,14 The moiréunit cell of gr/Ru(0001) features a periodic variation in the registry between the carbon and Ru atoms of the topmost surface layer. When one of the carbon atoms from the two-atom basis of the gr honeycomb structure is approximately on top of an Ru substrate atom, a covalent bond forms, pulling the graphene closer to the metal surface.…”

Section: ■ Introductionmentioning

confidence: 99%

Valleys and Hills of Graphene on Ru(0001)

et al. 2018

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The structure of graphene on Ru(0001) has been extensively studied over the last decade, yet with no general agreement. Here, we analyze graphene's valleys and hills using a combination of X-ray standing wave (XSW) and density functional theory (DFT). The chemical specificity of XSW allows an independent analysis of valleys and hills, which, together with the DFT model, results in the precise determination of the distance between the flat, strongly bounded valleys of graphene and the substrate as well as the corrugation presented in the weakly bounded hills. From the theoretical viewpoint, the good agreement with the experiment validates the choices regarding the unit cell size and the nonlocal correlation functional.

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“…In graphene/metal composites, the structure and bonding features at the interface are very complex. By utilizing advanced technology, such as X-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy (STM), and lowenergy electron diffraction (LEED), the orderly cyclical atomic structures (termed as moiré patterns) were often observed at the graphene/metal interfaces [25][26][27]. Jacobberger et al presented a comprehensive study of the evolution of graphene/Cu interface as a function of the matrix orientation, which provided a new way to adjust the structure and morphology of graphene reasonably [28].…”

Section: Introductionmentioning

confidence: 99%

Interfacial Characteristics of Graphene-Reinforced Iron Composites: A Molecular Dynamics Study

et al. 2022

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Interface has a significant effect on mechanical properties of graphene reinforced metal composites. Taking graphene nanosheet reinforced iron composite (Gr/Fe) as an example, the interfacial characteristics of Gr/Fe (110), (111), (112¯), and (001) interfaces have been studied using molecular dynamics (MD) simulations. Two types of interfacial bonding have been examined: physical and chemical bonding. The results show that when the graphene and iron form a physical adsorption (weak−bonded) interface, the interactive energy of the graphene and Fe (110), (111), (112¯), and (001) interface is −1.00 J/m2, −0.73 J/m2, −0.82 J/m2, and −0.81 J/m2, respectively. The lengths of the Fe−C bonding are distributed in the range of 2.20–3.00 Å without carbide formation, and no distinct patterns of atomic structure are identified. When the graphene and iron form a chemical (strong−bonded) interface, the corresponding interactive energy is −5.63 J/m2, −4.32 J/m2, −4.39 J/m2, and −4.52 J/m2, respectively. The lengths of the Fe−C bonding are mainly distributed in the ranges of 1.80−2.00 Å and 2.30−2.50 Å, which the carbides such as Fe3C and Fe7C3 are formed at the interface. Moiré patterns are observed at different−oriented interfaces, because of the lattice geometrical mismatch between graphene and different−oriented iron crystal structures. The pattern of diamond stripe is at the (110) interface, which is in good accordance with the experiment. Other patterns are the hexagonal pattern at the (111) interface, the wavy stripe pattern at the (112¯) interface, and the chain pattern at the (001) interface. These moiré patterns are formed through the competition and coordination of the three binding sites (Hollow, Bridge, and Top) of graphene with Fe atoms.

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Effect of moiré superlattice reconstruction in the electronic excitation spectrum of graphene-metal heterostructures

Cited by 13 publications

References 46 publications

Confining graphene plasmons to the ultimate limit

Confining graphene plasmons to the ultimate limit

Valleys and Hills of Graphene on Ru(0001)

Interfacial Characteristics of Graphene-Reinforced Iron Composites: A Molecular Dynamics Study

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