Recent Progress on Nonlocal Graphene/Surface Plasmons

Horing, Norman J. M.; Iurov, Andrii; Gumbs, Godfrey; Politano, Antonio; Chiarello, G.

doi:10.1007/978-3-319-25340-4_9

Cited by 4 publications

(6 citation statements)

References 59 publications

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“…The numerical results for the plasmon dispersions with much smaller separations a are presented in Fig. 6, from which we reproduce a recent experimentally confirmed effect in graphene, 75,[82][83][84] i.e., the acoustic-like plasmon branch will be highly damped in the long-wavelength limit as a < 0.5 nm. This damping effect can be found for all considered cases in Figs.…”

Section: B Full Numerical Solutionssupporting

confidence: 71%

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Controlling plasmon modes and damping in buckled two-dimensional material open systems

Iurov

Gumbs

Huang

et al. 2017

Journal of Applied Physics

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Full ranges of both hybrid plasmon-mode dispersions and their damping are studied systematically by our recently developed mean-field theory in open systems involving a conducting substrate and a two-dimensional (2D) material with a buckled honeycomb lattice, such as silicene, germanene, and a group IV dichalcogenide as well. In this hybrid system, the single plasmon mode for a free-standing 2D layer is split into one acoustic-like and one optical-like mode, leading to a dramatic change in the damping of plasmon modes. In comparison with gapped graphene, critical features associated with plasmon modes and damping in silicene and molybdenum disulfide are found with various spin-orbit and lattice asymmetry energy bandgaps, doping types and levels, and coupling strengths between 2D materials and the conducting substrate. The obtained damping dependence on both spin and valley degrees of freedom is expected to facilitate measuring the open-system dielectric property and the spin-orbit coupling strength of individual 2D materials. The unique linear dispersion of the acoustic-like plasmon mode introduces additional damping from the intraband particle-hole modes which is absent for a free-standing 2D material layer, and the use of molybdenum disulfide with a large bandgap simultaneously suppresses the strong damping from the interband particle-hole modes.

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Section: B Full Numerical Solutionssupporting

confidence: 71%

“…68,[73][74][75][76] Furthermore, our previous work studied the plasmon instability in the graphene double-layer system, predicting an instability-based terahertz emission, 77 and nonlocal plasmons in a metal-graphene-metal encapsulated structure.…”

mentioning

confidence: 99%

Controlling plasmon modes and damping in buckled two-dimensional material open systems

Iurov

Gumbs

Huang

et al. 2017

Journal of Applied Physics

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“…Moreover, the primary electron beam illuminating the sample is not parallel, and its convergence angle is magnified due to the field produced by the sample bias. This means that even though the condition of sufficient beam tilt as described in [ 75 ] may be not met, because of the beam convergence, it can be approached.…”

Section: Discussionmentioning

confidence: 99%

Low-Energy Electron Inelastic Mean Free Path of Graphene Measured by a Time-of-Flight Spectrometer

et al. 2021

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The detailed examination of electron scattering in solids is of crucial importance for the theory of solid-state physics, as well as for the development and diagnostics of novel materials, particularly those for micro- and nanoelectronics. Among others, an important parameter of electron scattering is the inelastic mean free path (IMFP) of electrons both in bulk materials and in thin films, including 2D crystals. The amount of IMFP data available is still not sufficient, especially for very slow electrons and for 2D crystals. This situation motivated the present study, which summarizes pilot experiments for graphene on a new device intended to acquire electron energy-loss spectra (EELS) for low landing energies. Thanks to its unique properties, such as electrical conductivity and transparency, graphene is an ideal candidate for study at very low energies in the transmission mode of an electron microscope. The EELS are acquired by means of the very low-energy electron microspectroscopy of 2D crystals, using a dedicated ultra-high vacuum scanning low-energy electron microscope equipped with a time-of-flight (ToF) velocity analyzer. In order to verify our pilot results, we also simulate the EELS by means of density functional theory (DFT) and the many-body perturbation theory. Additional DFT calculations, providing both the total density of states and the band structure, illustrate the graphene loss features. We utilize the experimental EELS data to derive IMFP values using the so-called log-ratio method.

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“…In the figures, we present calculated results for the nonlocal plasmon excitations of encapsulated gapless and gapped graphene. As we demonstrated in previous work [11,12], the hybrid plasmon modes and their damping are mainly determined by the doping concentration, i.e., the chemical potential µ, along with the energy bandgap ∆. Consequently, we have paid particular attention in our numerical investigations to the various regimes of the ratio ∆/µ.…”

Section: Numerical Results and Discussionmentioning

confidence: 87%

“…This brand new area of nanoscience not only poses challenges for experimentalists, but also for theoreticians seeking to formulate a theory for a model system. Although there already exists a copious literature on graphene on a single substrate [11][12][13][14][15][16][17][18], this study shows that encapsulated graphene is vastly different in many ways.…”

Section: Introductionmentioning

confidence: 82%

Plasmon excitations for encapsulated graphene

Gumbs¹,

Horing²,

Iurov³

et al. 2016

J. Phys. D: Appl. Phys.

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We have developed an analytical formulation to calculate the plasmon dispersion relation for a two-dimensional layer which is encapsulated within a narrow spatial gap between two bulk halfspace plasmas. This is based on a solution of the inverse dielectric function integral equation within the random-phase approximation (RPA). We take into account the nonlocality of the plasmon dispersion relation for both gapped and gapless graphene as the sandwiched two-dimensional (2D) semiconductor plasma. The associated nonlocal graphene plasmon spectrum coupled to the "sandwich" system is exhibited in density plots, which show a linear mode and a pair of depolarization modes shifted from the bulk plasma frequency.

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Recent Progress on Nonlocal Graphene/Surface Plasmons

Cited by 4 publications

References 59 publications

Controlling plasmon modes and damping in buckled two-dimensional material open systems

Controlling plasmon modes and damping in buckled two-dimensional material open systems

Low-Energy Electron Inelastic Mean Free Path of Graphene Measured by a Time-of-Flight Spectrometer

Plasmon excitations for encapsulated graphene

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