Observation of intrinsic intraband<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>π</mml:mi></mml:mrow></mml:math>-plasmon excitation of a single-layer graphene

Shin, Sang‐Wan; Hwang, Choongyu; Sung, Si Jin; Kim, N. D.; Kim, H. S.; Chung, J. W.

doi:10.1103/physrevb.83.161403

Cited by 41 publications

(23 citation statements)

References 27 publications

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“…5(b,c). A similar plasmon mode is also observed in an extrinsic graphene47485556, while germanene has the stronger intensity because of the weakened e-h damping. With the increase of V z (Fig.…”

Section: Resultssupporting

confidence: 60%

“…Germanene quite differs from silicene and graphene in excitation spectra. The theoretical predictions could be verified from the experimental measurements using the EELS56575859606162 and the inelastic light scattering spectroscopy63646566.…”

mentioning

confidence: 65%

“…The experimental measurements on single- and few-layer graphenes are utilized to comprehend the collective excitations due to the free carriers, the π electrons, and the π + σ electrons. They have identified the low-frequency acoustic plasmon (), accompanied with the interband Landau damping at larger momentum56. The interband π and π + σ plasmons are, respectively, observed at and ; furthermore, their frequencies are enhanced by the increase of layer number57.…”

Section: Resultsmentioning

confidence: 99%

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Coulomb excitations of monolayer germanene

Shih

Chiu

et al. 2017

Sci Rep

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The feature-rich electronic excitations of monolayer germanene lie in the significant spin-orbit coupling and the buckled structure. The collective and single-particle excitations are diversified by the magnitude and direction of transferred momentum, the Fermi energy and the gate voltage. There are four kinds of plasmon modes, according to the unique frequency- and momentum-dependent phase diagrams. They behave as two-dimensional acoustic modes at long wavelength. However, for the larger momenta, they might change into another kind of undamped plasmons, become the seriously suppressed modes in the heavy intraband e–h excitations, keep the same undamped plasmons, or decline and then vanish in the strong interband e–h excitations. Germanene, silicene and graphene are quite different from one another in the main features of the diverse plasmon modes.

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Section: Resultssupporting

confidence: 60%

mentioning

confidence: 65%

Section: Resultsmentioning

confidence: 99%

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Coulomb excitations of monolayer germanene

Shih

Chiu

et al. 2017

Sci Rep

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“…In addition, such bilayer inclusions are restricted to the substrate step regions known from previous low-energy electron microscopy investigations [16], while on the terraces the defect density in the graphene lattice is low, as seen in the SEM image in figure 2(b). Thus, the roughness claimed by Shin et al [39] can not be responsible for the dent and its shift. On the other hand, if this effect were based on plasmon-phonon coupling, the point of inflection should appear at lower loss energies for high chemical potentials (compare with [40]), so this origin can also be ruled out.…”

Section: Plasmons In Quasi-free-standing Monolayer Graphene (Qfmlg)mentioning

confidence: 82%

Manipulation of plasmon electron–hole coupling in quasi-free-standing epitaxial graphene layers

et al. 2012

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We have investigated the plasmon dispersion in quasi-free-standing monolayer graphene (QFMLG) and epitaxial monolayer graphene (MLG) layers by means of angle resolved electron energy loss spectroscopy. We have shown that various intrinsic p-and n-doping levels in QFMLG and MLG, respectively, do not lead to different overall slopes of the sheet plasmon dispersion, contrary to theoretical predictions. Only the coupling of the plasmon to single particle interband transitions becomes obvious in the plasmon dispersion by characteristic points of inflections, which coincide with the location of the Fermi level above or below the Dirac point. Further evidence is given by thermal treatment of the QFML graphene layer with gradual desorption of intercalated hydrogen, which shifts the chemical potential toward the Dirac point. From a detailed analysis of the plasmon dispersion, we deduce that the interaction strength between the plasmon and the electron-hole pair excitation is increased by about 30% in QFMLG compared to MLG, which is attributed to a modified dielectric environment of the graphene film.

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“…Our work unveils the tailored plasmonic characteristics of TBLG and deepens our understanding of the intriguing nano-optical physics in novel van der Waals coupled two-dimensional materials. Graphene Dirac plasmons [1][2][3][4][5][6], which are collective oscillations of Dirac fermions in graphene, have been widely investigated in recent years by using both the electron energy loss spectroscopy [7][8][9] and optical imaging or spectroscopy [10][11][12][13][14][15][16][17][18][19][20][21] techniques. These quasiparticles demonstrate many superior characteristics including high confinement, long lifetime, strong field enhancement, electrical tunability, and a broad spectral range from terahertz to infrared .…”

mentioning

confidence: 99%

Real-Space Imaging of the Tailored Plasmons in Twisted Bilayer Graphene

Das

Luan

et al. 2017

Phys. Rev. Lett.

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We report a systematic plasmonic study of twisted bilayer graphene (TBLG)two graphene layers stacked with a twist angle. Through real-space nanoimaging of TBLG single crystals with a wide distribution of twist angles, we find that TBLG supports confined infrared plasmons that are sensitively dependent on the twist angle. At small twist angles, TBLG has a plasmon wavelength comparable to that of single-layer graphene (SLG). At larger twist angles, the plasmon wavelength of TBLG increases significantly with apparently lower damping. Further analysis and modeling indicate that the observed twist-angle-dependence of TBLG plasmons in the Dirac linear regime is mainly due to the Fermi-velocity renormalization, a direct consequence of interlayer electronic coupling. Our work unveils the tailored plasmonic characteristics of TBLG and deepens our understanding of the intriguing nano-optical physics in novel van der Waals (vdW) coupled two-dimensional (2D) materials. Main textGraphene Dirac plasmons [1-6], which are collective oscillations of Dirac fermions in graphene, have been widely investigated in recent years by using both the electron energy loss spectroscopy [7-9] and optical imaging/spectroscopy [10][11][12][13][14][15][16][17][18][19][20][21] techniques. These quasiparticles demonstrate many superior characteristics including high confinement, long lifetime, strong field enhancement, broad spectral range, electrical tunability and a broad spectral range from terahertz to infrared .

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Observation of intrinsic intrabandπ-plasmon excitation of a single-layer graphene

Cited by 41 publications

References 27 publications

Coulomb excitations of monolayer germanene

Coulomb excitations of monolayer germanene

Manipulation of plasmon electron–hole coupling in quasi-free-standing epitaxial graphene layers

Real-Space Imaging of the Tailored Plasmons in Twisted Bilayer Graphene

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