First Direct Observation of a Nearly Ideal Graphene Band Structure

Sprinkle, M.; Siegel, David A.; Hu, Yue; Hicks, Julie A.; Tejeda, Antonio; Taleb‐Ibrahimi, A.; Fèvre, P. Le; Bertran, F.; Vizzini, Sébastien; Enriquez, Hanna; Chiang, S.; Soukiassian, P.; Berger, Claire; Heer, Walt A. de; Lanzara, Alessandra; Conrad, E. H.

doi:10.1103/physrevlett.103.226803

Cited by 445 publications

(458 citation statements)

References 32 publications

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“…The complex interlayer atomic interactions indicate that the low-energy expansion about the K point is not suitable in obtaining energy dispersions; therefore, the effective-mass model can not be used to achieve further magnetic quantization. The three zero-field pairs of energy bands contain oscillatory, sombreroshaped and parabolic dispersions, which could be examined by ARPES [82]. They are magnetically quantized into three groups of LLs, defined by the dominating subenveloped functions.…”

Section: Resultsmentioning

confidence: 99%

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Configuration-enriched magneto-electronic spectra of AAB-stacked trilayer graphene

Lin

et al. 2015

Carbon

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We developed the generalized tight-binding model to study the magneto-electronic properties of AAB-stacked trilayer graphene. Three groups of Landau levels (LLs) are characterized by the dominating subenvelope function on distinct sublattices. Each LL group could be further divided into two sub-groups in which the wavefunctions are, respectively, localized at 2/6 (5/6) and 4/6 (1/6) of the total length of the enlarged unit cell. The unoccupied conduction and the occupied valence LLs in each subgroup behave similarly. For the first group, there exist certain important differences between the two sub-groups, including the LL energy spacings, quantum numbers, spatial distributions of the LL wavefunctions, and the field-dependent energy spectra.The LL crossings and anticrossings occur frequently in each sub-group during the variation of field strengths, which thus leads to the very complex energy spectra and the seriously distorted wavefunctions. Also, the density of states (DOS) exhibits rich symmetric peak structures. The predicted results could be directly examined by experimental measurements. The magnetic quantization is quite different among the AAB-, AAA-, ABA-, and ABC-stacked configurations.

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Section: Resultsmentioning

confidence: 99%

“…The special band structure could be verified by angle-resolved photoemission spectroscopy (ARPES) [82]. The LL evolution under a magnetic field reveals a complex pattern of LL anticrossings and splittings, as a result of the specific interlayer atomic interactions derived from the full tight-binding model.…”

Section: Introductionmentioning

confidence: 97%

Configuration-enriched magneto-electronic spectra of AAB-stacked trilayer graphene

Lin

et al. 2015

Carbon

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“…[7][8][9] The latter with rotationally stacked layers exhibits properties similar to SLG. [10][11][12] Moreover, it shows improved charge carrier mobility. 13 Furthermore, it has been observed that the rotationally stacked BLG decouples its electronic structure and preserves the intrinsic properties of SLG.…”

Section: Introductionmentioning

confidence: 99%

Control of layer stacking in CVD graphene under quasi-static condition

Subhedar

Sharma

Dhakate

2015

Phys. Chem. Chem. Phys.

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The type of layer stacking in bilayer graphene has a significant influence on its electronic properties because of the contrast nature of layer coupling. Herein, different geometries of the reaction site for the growth of bilayer graphene by the chemical vapor deposition (CVD) technique and their effects on the nature of layer stacking are investigated. Micro-Raman mapping and curve fitting analysis confirmed the type of layer stacking for the CVD grown bilayer graphene. The samples grown with sandwiched structure such as quartz/Cu foil/quartz along with a spacer, between the two quartz plates to create a sealed space, resulted in Bernal or AB stacked bilayer graphene while the sample sandwiched without a spacer produced the twisted bilayer graphene. The contrast difference in the layer stacking is a consequence of the difference in the growth mechanism associated with different geometries of the reaction site. The diffusion dominated process under quasi-static control is responsible for the growth of twisted bilayer graphene in sandwiched geometry while surface controlled growth with ample and continual supply of carbon in sandwiched geometry along with a spacer, leads to AB stacked bilayer graphene. Through this new approach, an efficient technique is presented to control the nature of layer stacking.

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“…The experimental graphene sample is synthesized by using three di erent methods. The rst type is multilayer epitaxial graphene (MEG), where the individual layers are electronically decoupled due to their unique rotational stacking, and each layer exhibits a single graphene layer Dirac cone near the Dirac point so that MEG behaves in essence as multilayer graphene [111,112]. The second type is singlecrystal CVD graphene (sCVDG), which is grown on oxygen-rich copper foil into large individual single crystals exceeding hundreds of micrometers in size [113].…”

Section: Optical Pump and Thz Probe DI Erential Transmission Spectramentioning

confidence: 99%

Relaxation Dynamics in Graphene

Malić

Knorr

2013

Graphene and Carbon Nanotubes

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In this thesis, the relaxation dynamics of nonequilibrium carriers in graphene is investigated. Based on the density matrix approach, the interaction of carriers with light, phonons and electrons is theoretically modelled. The resulting time-, momentum-, and angle-resolved simulation of the carrier dynamics enables the interpretation of recent experimental observations. Typically, the carrier relaxation has been accessed via high-resolution pump-probe experiments. Common to all studies is a bi-exponential decay of the pump-induced differential transmission (DT) spectrum. The fast decay component in the range of few tens of femtoseconds is assigned to an ultrafast Coulomb-dominated carrier redistribution towards a hot Fermi-Dirac distribution, whereas the slower decay component in the range of a picosecond reflects the equilibration between the electron and the phonon system. However, many studies report a zero-crossing after the initial decay in the transient DT spectrum, where the second decay component characterizes the recovering of the DT signal. In very good agreement with recent pump-probe experiment performed by the group of Prof. Manfred Helm (Helmholtz-Zentrum Dresden-Rossendorf), a microscopic explanation for the occurrence of transient negative differential transmission in graphene is found, where a detailed interplay of intraand interband absorption processes on the transient DT in graphene is investigated. In particular, phonon-assisted intraband processes are shown to lead to an enhanced absorption giving rise to the experimentally observed zero-crossing from positive to negative DT signals.In collaboration with the group of Prof. Theodore B. Norris (Michigan University, USA), theoretical studies combined with ultrafast time-resolved THz spectroscopy were performed to systematically investigate the hot-carrier dynamics in an array of graphene samples. The theory calculates explicitly the time-dependent response of the system to a THz probe pulse. The calculations reveal that the observed dynamics can be accounted for qualitatively without including any fitting parameters, phenomenological models or extrinsic effects. Specifically, the hot-carrier dynamics are governed by the coupling of extraordinarily efficient carrier-carrier and carrier-phonon interactions. Furthermore, the theory demonstrates that the simple Drude model is insufficient to fully account for the THz interactions.Beside pump-probe studies, the thesis presents the absorption spectra of mono-and bilayer graphene including the impact of the fully momentum-dependent optical and Coulomb matrix elements. In agreement with recent experiments, the absorbance of graphene is characterized by a frequency-independent value in the near-infrared spectral region and a pronounced peak in the ultraviolet region resulting from interband transition. In contrast to the linear band structure of graphene, the energy dispersion of bilayer graphene exhibits four parabolic bands resulting in interesting optical features: The absorbance exhibits in...

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First Direct Observation of a Nearly Ideal Graphene Band Structure

Cited by 445 publications

References 32 publications

Configuration-enriched magneto-electronic spectra of AAB-stacked trilayer graphene

Configuration-enriched magneto-electronic spectra of AAB-stacked trilayer graphene

Control of layer stacking in CVD graphene under quasi-static condition

Relaxation Dynamics in Graphene

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