The effect of sublattice symmetry breaking on the electronic properties of doped graphene

Qaiumzadeh, Alireza; Asgari, Reza

doi:10.1088/1367-2630/11/9/095023

Cited by 29 publications

(22 citation statements)

References 90 publications

(139 reference statements)

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“…and , respectively, for a set of values of the scaled band gap parameter

a = Δ / μ_{normalf} (= 0.3, 0.6, 0.9)

and temperature values

(T = 0, 0.5 T_{normalf}, T_{normalf})

, where

μ_{normalf} = \sqrt{{ϵ_{normalf}}^{2} + Δ^{2}}

is the Fermi energy of SLGG and

T_{normalf} = ϵ_{normalf} / k_{normalb}

is the Fermi temperature. For zero temperature, our computed results (using τ = 0.8 ps) for NDP are in excellent agreement with that reported earlier (where

τ \to \infty

) . The relaxation time ( τ ) is an important parameter because the actual value of τ affects the plasmon propagation distance.…”

Section: Numerical Results and Discussionsupporting

confidence: 90%

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Finite temperature dynamical polarization and plasmons in gapped graphene

Patel

Ashraf

Sharma

2015

Phys. Status Solidi B

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In this study we report our numerical results on finite temperature non-interacting dynamical polarization function, plasmon modes and electron energy loss function of doped single layer gapped graphene within the random phase approximation. We find that the interplay of linear energy band dispersion, chirality, bandgap and temperature endow single layer gapped graphene with strange polarizability behaviour which is a mixture of 2DEG, single layer and bilayer graphene and as a result the plasmon spectrum also manifests strikingly peculiar behaviour. The plasmon dispersion is observed to be suppressed till temperatures up to ~ , similar to the gapless graphene case but beyond a reversal in trend is seen in gapped graphene, for all values of band gap. This behaviour is also corroborated by the density plots of electron energy loss function. The opening of a small gap also generates a new undamped plasmon mode which is found to disappear at high temperatures. The plasmonic behaviour of gapped graphene is further found to be hugely influenced by the substrate on which the gapped graphene sheet rests, which signifies the need for a careful substrate selection in the making of desirable graphene based plasmonics devices.

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“…and , respectively, for a set of values of the scaled band gap parameter

a = Δ / μ_{normalf} (= 0.3, 0.6, 0.9)

and temperature values

(T = 0, 0.5 T_{normalf}, T_{normalf})

, where

μ_{normalf} = \sqrt{{ϵ_{normalf}}^{2} + Δ^{2}}

is the Fermi energy of SLGG and

T_{normalf} = ϵ_{normalf} / k_{normalb}

is the Fermi temperature. For zero temperature, our computed results (using τ = 0.8 ps) for NDP are in excellent agreement with that reported earlier (where

τ \to \infty

) . The relaxation time ( τ ) is an important parameter because the actual value of τ affects the plasmon propagation distance.…”

Section: Numerical Results and Discussionsupporting

confidence: 90%

“…(g) Imaginary part of polarization function as a function of ω at different values of relaxation time τ at T = 0 K, a = 0.6, and q = 0.5 k f . Here

N_{0} = 2 μ_{normalf} / (π γ^{2})

is the density of states at the Fermi level of SLGG .…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

Finite temperature dynamical polarization and plasmons in gapped graphene

Patel

Ashraf

Sharma

2015

Phys. Status Solidi B

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“…The intensity of the plasmaron band in the experimental data is comparable to the theoretical prediction, demonstrating that neither the defect scattering rate nor the symmetry breaking potential induced by the substrate introduce important energy scales. Both of these effects have been predicted to quickly dampen the plasmaron mode (9,10,26).…”

Section: Comparing the Plasmon Dispersionmentioning

confidence: 99%

Observation of Plasmarons in Quasi-Freestanding Doped Graphene

Bostwick

Speck

Seyller

et al. 2010

Science

Self Cite

406

443

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A hallmark of graphene is its unusual conical band structure that leads to a zero-energy band gap at a singleElectrons in metals and semiconductors undergo many complex interactions, and most theoretical treatments make use of the quasiparticle approximation, in which independent electrons are replaced by electron-and holelike quasiparticles interacting through a dynamically screened Coulomb force. The details of the screening are determined by the valence band structure, but the band energies are modified by the screened interactions. A complex self-energy function describes the energy and lifetime renormalization of the band structure resulting from this interplay.Bohm and Pines (1) accounted for the short-range interactions between quasiparticles through the creation of a polarization cloud formed of virtual electron-hole pairs around each charge carrier, screening each from its neighbors. The long-range interactions manifest themselves through plasmons, collective charge density oscillations of the electron gas that can propagate through the medium with their own band-dispersion relation.These plasmons can in turn interact with the charges, leading to strong self-energy effects. Lundqvist predicted the presence of new composite particles called plasmarons formed by the coupling of the elementary charges with plasmons (2). Their distinct energy bands should be observable using angle-resolved photoemission spectroscopy (ARPES), but so far have only been observed by optical (3, 4) and tunneling spectroscopies (5), which probe the altered density of states.Understanding the coupling between electrons and plasmons is important because of new "plasmonic" devices proposed to merge photonics and electronics. Graphene in particular has been proposed as a promising candidate for such devices (6-8). Plasmarons have been predicted to occur in graphene and to be observable in ARPES (9, 10), yet their detailed dispersion and interaction with defects remain unknown. Here we present a

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“…They also argued that the massive phase exhibits much more interesting behavior than the massless one. The effect of fermion gap on quasiparticle lifetime and spectral function was discussed in [20]. This kind of excitonic instability may also exist in other correlated electron systems than graphene.…”

Section: Model and Definitionsmentioning

confidence: 99%

Coulomb interaction and semimetal–insulator transition in graphene

Liu

2010

Physics Letters A

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The strong Coulomb interaction between massless Dirac fermions can drive a semimetal-insulator transition in single-layer graphene by dynamically generating an excitonic fermion gap. There is a critical interaction strength λ c that separates the semimetal phase from the insulator phase. We calculate the specific heat and susceptibility of the system and show that they exhibit distinct behaviors in the semimetal and insulator phases.

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The effect of sublattice symmetry breaking on the electronic properties of doped graphene

Cited by 29 publications

References 90 publications

Finite temperature dynamical polarization and plasmons in gapped graphene

Finite temperature dynamical polarization and plasmons in gapped graphene

Observation of Plasmarons in Quasi-Freestanding Doped Graphene

Coulomb interaction and semimetal–insulator transition in graphene

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