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We present an analytic calculation of the conductivity of pure graphene as a function of frequency $\omega $, wave-vector $k$, and temperature for the range where the energies related to all these parameters are small in comparison with the…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 L. A. Falkovsky , A. A. Varlamov

We address the puzzling weak-coupling perturbative behavior of graphene interaction effects as manifested experimentally, in spite of the effective fine structure constant being large, by calculating the effect of Coulomb interactions on…

Mesoscale and Nanoscale Physics · Physics 2014-09-11 Johannes Hofmann , Edwin Barnes , S. Das Sarma

Electrons moving in graphene behave as massless Dirac fermions, and they exhibit fascinating low-frequency electrical transport phenomena. Their dynamic response, however, is little known at frequencies above one terahertz (THz). Such…

We demonstrate that optical transparency of any two-dimensional system with a symmetric electronic spectrum is governed by the fine structure constant and suggest a simple formula that relates a quasi-particle spectrum to an optical…

Mesoscale and Nanoscale Physics · Physics 2010-07-22 V. G. Kravets , A. N. Grigorenko , R. R. Nair , P. Blake , S. Anissimova , K. S. Novoselov , A. K. Geim

Experiments are finally revealing intricate facts about graphene which go beyond the ideal picture of relativistic Dirac fermions in pristine two dimensional (2D) space, two years after its first isolation. While observations of rippling…

Other Condensed Matter · Physics 2009-11-13 Eun-Ah Kim , A. H. Castro Neto

We report significant changes of optical conductivity in single layer graphene induced by mild oxygen plasma exposure, and explore the interplay between carrier doping, disorder, and many-body interactions from their signatures in the…

We numerically calculate the optical conductivity of twisted graphene bilayers within the continuum model. To obtain the imaginary part, we employ the regularized Kramers-Kronig relation allowing us to discuss arbitrary twist angles,…

Mesoscale and Nanoscale Physics · Physics 2013-12-03 Tobias Stauber , Pablo San-Jose , Luis Brey

Advances in infrared nanoscopy have enabled access to the finite momentum optical conductivity $\sigma(\vec{q},\omega)$. The finite momentum optical conductivity in graphene has a peak at the Dirac fermion quasiparticle energy…

Mesoscale and Nanoscale Physics · Physics 2012-10-17 Phillip E. C. Ashby , J. P. Carbotte

We examine the 1/N expansion, where N is the number of two-component Dirac fermions, for Coulomb interactions in graphene with a gap of magnitude $\Delta = 2 m$. We find that for $N\alpha\gg1$, where $\alpha$ is graphene's "fine structure…

Mesoscale and Nanoscale Physics · Physics 2022-03-07 Valeri N. Kotov , Bruno Uchoa , A. H. Castro Neto

With the advent of high mobility encapsulated graphene devices, new electronic components ruled by Dirac fermions optics have been envisioned and realized. The main building blocks of electron-optics devices are gate-defined p-n junctions,…

The inter-band optical absorption in graphene characterized by its fine-structure constant has a universal value of 2.3\% independent of the material parameters. However, for several graphene-based photonic applications, enhanced optical…

Materials Science · Physics 2016-03-23 Shaloo Rakheja , Parijat Sengupta

Disordered Fermi-Dirac distributions are used to model, within a straightforward and essentially phenomenological Boltzmann equation approach, the electron/hole transport across graphene puddles. We establish, with striking experimental…

Mesoscale and Nanoscale Physics · Physics 2015-05-30 L. Moriconi , D. Niemeyer

Graphene constitutes one of the key elements in many functional van der Waals heterostructures. However, it has negligible optical visibility due to its monolayer nature. Here we study the visibility of graphene in various van der Waals…

Two dimensional optical materials, such as graphene can be characterized by a surface conductivity. So far, the transformation optics schemes have focused on three dimensional properties such as permittivity $\epsilon$ and permeability…

Optics · Physics 2014-12-16 Anshuman Kumar , Kin Hung Fung , M. T. Homer Reid , Nicholas Fang

Graphene's fluorescence quenching is studied as a function of distance. Transverse decay channels, full retardation and graphene-field coupling to all orders are included, extending previous instantaneous results. For neutral graphene, a…

Mesoscale and Nanoscale Physics · Physics 2011-11-03 G. Gómez-Santos , T. Stauber

The complete theory of electrical conductivity of graphene at arbitrary temperature is developed with taken into account mass-gap parameter and chemical potential. Both the in-plane and out-of-plane conductivities of graphene are expressed…

Mesoscale and Nanoscale Physics · Physics 2017-12-25 G. L. Klimchitskaya , V. M. Mostepanenko , V. M. Petrov

We reduce the dimensionless interaction strength in graphene by adding a water overlayer in ultra-high vacuum, thereby increasing dielectric screening. The mobility limited by long-range impurity scattering is increased over 30 percent, due…

Materials Science · Physics 2008-10-06 C. Jang , S. Adam , J. -H. Chen , E. D. Williams , S. Das Sarma , M. S. Fuhrer

We employ ultrabroadband terahertz (THz) spectroscopy to expose the high-frequency transport properties of Dirac fermions in monolayer graphene. By controlling the carrier concentration via tunable electrical gating, both equilibrium and…

Mesoscale and Nanoscale Physics · Physics 2024-10-29 G. Coslovich , R. P. Smith , S. -F. Shi , J. H. Buss , J. T. Robinson , F. Wang , R. A. Kaindl

We study the influence of different kinds of gaps in a quasiparticle spectrum on longitudinal and transverse optical conductivities of bilayer graphene. An exact analytical expression for magneto-optical conductivity is derived using a…

Strongly Correlated Electrons · Physics 2012-08-08 E. V. Gorbar , V. P. Gusynin , A. B. Kuzmenko , S. G. Sharapov

The electrical conductivity of graphene containing point defects is studied within the binary alloy model in its dependence on the Fermi level position at the zero temperature. It is found that the minimal conductivity value does not have a…

Disordered Systems and Neural Networks · Physics 2015-05-18 Yuriy V. Skrypnyk , Vadim M. Loktev