Dynamical polarization of graphene under strain

Pellegrino, Francesco; Angilella, G. G. N.; Pucci, R.

doi:10.1103/physrevb.82.115434

Cited by 40 publications

(31 citation statements)

References 47 publications

(64 reference statements)

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“…Except that, the local-field effect [59] of the lattice structure together with the induced standard deviations are ignored in our calculations, since they have negligible effects in our homogeneous model under the low-temperature and low-momentum regime. The neglect of the local-field effect also results in the decreasing of the number of the plasmon branches due to the suppression of the intreband transition and the optical plasmon branch [59]. The bilayer silicene, in contrast to the monolayer silicene or the normal double-layer system like the double quantum-well, has a interlayer hopping which leads to the polarization-dependent band param-eter.…”

Section: Discussionmentioning

confidence: 99%

Interband and intraband transition, dynamical polarization and screening of the monolayer and bilayer silicene in low-energy tight-binding model

2018

Indian J Phys

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We investigate the interband and intraband transition of the monolayer and AB-stacked bilayer silicene in low-energy tight-binding model under the electric field, where we focus on the dynamical polarization function, screening due to the charged impurity, and the plasmon dispersion. We obtain the logarithmically divergen polarization function within the random-phase-approximation (RPA) whose logarithmic singularities corresponds to the discontinuities of the first derivative which is at the momentum q = 2kF in static case and indicate the topological phase transition point from the gapless semimetal to the gapped band insulator. We also obtain the power-law-dependent Friedel oscillation which can be enhanced by increasing the Rashba-coupling, that can contribute to the screened potential of the charged impurity which scale as ∼ r −1/2 in the short distance from the impurity and scale as ∼ r −1/3 in the long distance from the impurity. In the single-particle excitation regime with the electron-hole continuum, the interband and intraband transition happen, and the plasmon dispersion, which we mainly focus on the optical plasmon (which ∼ √ q in long-wavelength limit) in this paper, start to damped into the electron-hole pairs due to the nonzero imaginary part of the polarization function. In low-frequency regime where the collective behavior and optical properties of the Dirac material relys more on the frequency than the fine structure constant, the intraband transition is dominate and it's found that completely undamped in the static case (ω = 0), which is due to the absence of the imaginary dynamic polarization. We also observe the linear (weakly damped) plasmon model for the classical bilayer silicene which is similar to the high-energy π-plasmon or the case of conducting substrate which with strong metallic screening in the bulk semiconductor. For the large carrier density, we find the plasmon diapersion has ωp ∼ n 1/2 which consistent with the quadratic dispersion around the Dirac-point like the bilayer silicene with the effective mass about the interlayer hopping (esperially when taking the Rashba-coupling and exchange field into consider) or the normal two-dimension electron gas, while in the little concentration limit, ωp ∼ n 1/4 which consistent with the linear dispersion like the monolayer silicene. Under the nonmagnetic impurity scattering, the Thomas-Fermi decay and Friedel oscillation can easily be observed due to the strong spin-orbit couopling of the bilayer silicene even we don't take the Rashba-coupling into consider. *

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Section: Discussionmentioning

confidence: 99%

Interband and intraband transition, dynamical polarization and screening of the monolayer and bilayer silicene in low-energy tight-binding model

2018

Indian J Phys

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“…The manipulation of the density of states (DOS) of the π and π * bands of graphene can be a tool for tailoring its plasmonic excitations-a scenario realizable through the exposure of graphene to either mechanical stress [17,18] or a perpendicular magnetic field [19][20][21][22]. Also, as implied by the Pauli exclusion principle, the manipulation of the electronic occupation within the π and π * bands alters the response to the electromagnetic (EM) perturbations.…”

Section: Introductionmentioning

confidence: 99%

Drift-induced modifications to the dynamical polarization of graphene

Sabbaghi¹,

Lee²,

Stauber³

et al. 2015

Phys. Rev. B

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The response function of graphene is calculated in the presence of a constant current across the sample. For small drift velocities and finite chemical potential, analytic expressions are obtained and consequences on the plasmonic excitations are discussed. For general drift velocities and zero chemical potential, numerical results are presented and a plasmon gain region is identified that is related to interband transitions.

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“…These include low-energy quasiparticles with a Dirac-like spectrum and a linearly vanishing density of states (DOS) at the Fermi level. Evidence of such an unconventional behaviour is to be found in several electronic properties, such as Klein tunneling [5][6][7][8][9] , the optical conductivity [10][11][12] , and the plasmon dispersion relation [13][14][15][16] . These have been predicted to depend quite generally on applied strain 17 , following the earlier suggestion that suitably deformed graphene sheets could be engineered into nanodevices with the desired electron properties 18 .…”

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confidence: 99%