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Plasmon are collective oscillations of mobile electrons with dynamics controlled by their charge stiffness("Drude weight"). Using terahertz spacetime metrology, we probe Plasmon dynamics of mono- and bi-layer graphene. In both systems, the…

We report measurements of the cyclotron mass in graphene for carrier concentrations n varying over three orders of magnitude. In contrast to the single-particle picture, the real spectrum of graphene is profoundly nonlinear so that the…

Dirac plasmons in a doped graphene sheet have recently been shown to enable confinement of light to ultrasmall volumes. In this work we calculate the intrinsic lifetime of a Dirac plasmon in a doped graphene sheet by analyzing the role of…

Mesoscale and Nanoscale Physics · Physics 2013-11-14 Alessandro Principi , Giovanni Vignale , Matteo Carrega , Marco Polini

New Dirac points appear when periodic potentials are applied to graphene, and there are many interesting effects near these new Dirac points. Here we investigate the $\textit{Zitterbewegung}$ effect of fermions described by a Gaussian wave…

Mesoscale and Nanoscale Physics · Physics 2018-09-10 Jianli Luan , Shangyang Li , Tianxing Ma , Li-Gang Wang

In this work we investigate theoretically the influence of a Fermi velocity modulation in the electronic and transport properties of magnetic graphene superlattices. We solve the effective Dirac equation for graphene with a position…

Mesoscale and Nanoscale Physics · Physics 2020-05-21 Ícaro S. F. Bezerra , Jonas R. F. Lima

For electron optics in graphene, the propagation effect has so far been the only physical mechanism available. The resulting electron-optics-based components are large in size and operate at low temperatures to avoid violating the ballistic…

Mesoscale and Nanoscale Physics · Physics 2023-04-12 Ruihuang Zhao , Pengcheng Wan , Ling Zhou , Di Huang , Haiqin Guo , Hao Xia , Junjie Du

The optical properties of graphene are made unique by the linear band structure and the vanishing density of states at the Dirac point. It has been proposed that even in the absence of a semiconducting bandgap, a relaxation bottleneck at…

At low energy, electrons in doped graphene sheets behave like massless Dirac fermions with a Fermi velocity which does not depend on carrier density. Here we show that modulating a two-dimensional electron gas with a long-wavelength…

Mesoscale and Nanoscale Physics · Physics 2009-06-29 M. Gibertini , A. Singha , V. Pellegrini , M. Polini , G. Vignale , A. Pinczuk , L. N. Pfeiffer , K. W. West

We theoretically consider the effect of plasmon collective modes on the frequency-dependent conductivity of graphene in the presence of the random static potential of charged impurities. We develop an equation of motion approach suitable…

Mesoscale and Nanoscale Physics · Physics 2013-08-09 K. Kechedzhi , S. Das Sarma

The relevance of the strain-induced Dirac point shift to obtain the appropriate anisotropic Fermi velocity of strained graphene is demonstrated. Then a critical revision of the available effective Dirac Hamiltonians is made by studying in…

Mesoscale and Nanoscale Physics · Physics 2015-09-01 M. Oliva-Leyva , Gerardo G. Naumis

We identify and describe how intense short light pulses couple to massless Dirac fermions in two-dimensional systems. The ensuing excitation dynamics exhibits unusual scaling with the wavelength of the light due the linear dispersion of the…

Mesoscale and Nanoscale Physics · Physics 2022-05-19 Hamed Koochaki Kelardeh , Ulf Saalmann , Jan M. Rost

Three dimensional (3D) Dirac semimetals which can be seen as 3D analogues of graphene have attracted enormous interests in research recently. In order to apply these ultrahigh-mobility materials in future electronic/optoelectronic devices,…

Mesoscale and Nanoscale Physics · Physics 2017-01-19 Wei Lu , Shaofeng Ge , Xuefeng Liu , Hong Lu , Caizhen Li , Jiawei Lai , Chuan Zhao , Zhimin Liao , Shuang Jia , Dong Sun

Originating from relativistic quantum field theory, Dirac fermions have been recently applied to study various peculiar phenomena in condensed matter physics, including the novel quantum Hall effect in graphene, magnetic field driven…

Strongly Correlated Electrons · Physics 2008-04-10 S. Y. Zhou , G. -H. Gweon , J. Graf , A. V. Fedorov , C. D. Spataru , R. D. Diehl , Y. Kopelevich , D. -H. Lee , Steven G. Louie , A. Lanzara

Low-energy single-electron dynamics in graphene monolayers and similar nanostructures is described by the Dirac model, being a 2+1 dimensional version of massless QED with the speed of light replaced by the Fermi velocity v_{F}=c/300.…

Mesoscale and Nanoscale Physics · Physics 2017-04-18 S. P. Gavrilov , D. M. Gitman

Brownian dynamics of Dirac fermions in twisted bilayer graphene is investigated within the framework of semiclassical relativistic Langevin equations. We find that under the influence of orthogonal, commensurate ac drives in the periodic…

Mesoscale and Nanoscale Physics · Physics 2023-08-31 Abdullah Yar

The electronic structure of a graphene superlattice composed by two periodic regions with different Fermi velocity, energy gap and electrostatic potential is investigated by using an effective Dirac-like Hamiltonian. It must be expected…

Materials Science · Physics 2015-04-07 Jonas R. F. Lima

We study tunneling across a strain-induced superlattice in graphene. In studying the effect of applied strain on the low-lying Dirac-like spectrum, both a shift of the Dirac points in reciprocal space, and a deformation of the Dirac cones…

Mesoscale and Nanoscale Physics · Physics 2012-05-08 F. M. D. Pellegrino , G. G. N. Angilella , R. Pucci

We study the electronic and transport properties of a graphene-based superlattice theoretically by using an effective Dirac equation. The superlattice consists of a periodic potential applied on a single-layer graphene deposited on a…

Mesoscale and Nanoscale Physics · Physics 2015-02-26 Jonas R. F. Lima

In this work we study theoretically the electronic properties of a sheet of graphene grown on a periodic heterostructure substrate. We write an effective Dirac equation, which includes a dependence of both the band gap and the Fermi…

Materials Science · Physics 2014-11-12 Jonas R. F. Lima , F. Moraes

Dirac Fermion, which is the low energy collective excitation near the Dirac cone in monolayer graphene, have gained great attention by low energy Terahertz probe. In the case of undoped graphene, it has been generally understood that the…

Mesoscale and Nanoscale Physics · Physics 2021-05-25 Tingyuan Jia , Wenjie Zhang , Zijun Zhan , Zeyu Zhang , Guohong Ma , Juan Du , Yuxin Leng