Dynamical polarization, screening, and plasmons in gapped graphene

Pyatkovskiy, P. K.

doi:10.1088/0953-8984/21/2/025506

Cited by 222 publications

(339 citation statements)

References 28 publications

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“…We compare the response function for interacting electrons in the random phase approximation (RPA) at frequencies on the imaginary axis with that obtained for frequencies with a small imaginary part since they are used in calculating the correlation energy and collective plasma excitations, respectively. Our results which were obtained numerically are in agreement with those obtained analytically for plasmons in Dirac-cone graphene, 17, 18 gapped graphene 19 and TIs, 20 thereby giving credibility to our calculations for the exchange energy. It appears that the effect due to the quadratic term ∽ Dk 2 correction to the linear energy dispersion in wave vector k has little influence on the overlap structure factor.…”

Section: Introductionsupporting

confidence: 85%

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Topological Insulators

2013

Contemporary Concepts of Condensed Matter Science

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We have formulated a theory for investigating the conditions which are required to achieve entangled states of electrons on graphene and three-dimensional (3D) topological insulators (TIs). We consider the quantum entanglement of spins by calculating the exchange energy. A gap is opened up at the Fermi level between the valence and conduction bands in the absence of doping when graphene as well as 3D TIs are irradiated with circularly-polarized light. This energy band gap is dependent on the intensity and frequency of the applied electromagnetic field. The electron-photon coupling also gives rise to a unique energy dispersion of the dressed states which is different from either graphene or the conventional two-dimensional electron gas (2DEG). In our calculations, we obtained the dynamical polarization function for imaginary frequencies which is then employed to determine the exchange energy. The polarization function is obtained with the use of both the energy eigenstates and the overlap of pseudo-spin wave functions. We have concluded that while doping has a significant influence on the exchange energy and consequently on the entanglement, the gap of the energy dispersions affects the exchange slightly, which could be used as a good technique to tune and control entanglement for quantum information purposes.

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Section: Introductionsupporting

confidence: 85%

“…Our calculations of the real-Ω polarization completely agree with the earlier obtained results for the plasmonics. 17,19 It has been argued that the electron exchange energy has a direct and strong influence on the entanglement. This has been considered for both quantum dots and channels, originating from surface acoustic waves.…”

Section: Discussionmentioning

confidence: 99%

Topological Insulators

2013

Contemporary Concepts of Condensed Matter Science

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“…s (q , ω) is the density-density correlation function for graphene electrons [40][41][42]. The transverse and longitudinal electronic responses are associated with the magnetic and electric susceptibilities, respectively.…”

Section: Theory and Methodsmentioning

confidence: 99%

Effects of optical polarization on hybridization of radiative and evanescent field modes

et al. 2017

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Effects of induced optical polarization by Dirac electrons in graphene on the hybridization of radiative and evanescent fields is found. Such effects result in a localized polarization field which significantly modifies an incident surface-plasmon-polariton (SPP) field. This yields a high sensitivity to local dielectric environments and provides an investigative tool for molecules or proteins selectively bound with carbons. A scattering matrix is utilized with varied frequencies in the vicinity of the surface-plasmon (SP) resonance for the increase, decrease and even a full suppression of the polarization field, which enables accurate effective-medium theories to be constructed for Maxwellequation finite-difference time-domain methods. Moreover, double peaks in the absorption spectra for hybrid SP and graphene-plasmon modes are significant only with a large conductor plasma frequency, but are overshadowed by a round SPP peak at a small plasma frequency as the graphene is placed close to conductor surface. These resonant absorptions facilitate the polariton-only excitations, leading to polariton condensation for a threshold-free laser.

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“…To account for the finite scattering rate, we replace with in Equation (8) and follow the same procedure as the one in References [40,41] assuming μ ˃˃ k B T; the result is (9) where ; if and otherwise. Equation (9) is identical to Equation (7) of Reference [42] in a slightly different form. Apparently, by setting for , Equation (9) reduces to the collisionless results in References [40,41].…”

Section: Rpa Modelmentioning

confidence: 99%

Terahertz Optoelectronic Property of Graphene: Substrate-Induced Effects on Plasmonic Characteristics

Lin

Lai

et al. 2014

Applied Sciences

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Abstract:The terahertz plasmon dispersion of a multilayer system consisting of graphene on dielectric and/or plasma thin layers is systematically investigated. We show that graphene plasmons can couple with other quasiparticles such as phonons and plasmons of the substrate; the characteristics of the plasmon dispersion of graphene are dramatically modified by the presence of the coupling effect. The resultant plasmon dispersion of the multilayer system is a strong function of the physical parameters of the spacer and the substrate, signifying the importance of the substrate selection in constructing graphene-based plasmonic devices.

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Dynamical polarization, screening, and plasmons in gapped graphene

Cited by 222 publications

References 28 publications

Topological Insulators

Topological Insulators

Effects of optical polarization on hybridization of radiative and evanescent field modes

Terahertz Optoelectronic Property of Graphene: Substrate-Induced Effects on Plasmonic Characteristics

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