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We calculate the finite-frequency conductivity of bilayer graphene with a relative twist between the layers. The low frequency response at zero doping shows a flat conductivity with value twice that of the monolayer case and at higher…

Mesoscale and Nanoscale Physics · Physics 2013-03-12 Calvin J. Tabert , Elisabeth J. Nicol

The optical conductivity of graphene strained uniaxially is studied within the Kubo-Greenwood formalism. Focusing on inter-band absorption, we analyze and quantify the breakdown of universal transparency in the visible region of the…

Mesoscale and Nanoscale Physics · Physics 2011-01-17 Vitor M. Pereira , R. M. Ribeiro , N. M. R. Peres , A. H. Castro Neto

Pristine graphene and graphene-based heterostructures exhibit exceptionally high electron mobility and conductance if their surface contains few electron-scattering impurities. Here, we reveal a universal connection between graphene's…

We report on an infrared study on the undoped compound BaFe2As2 as a function of both pressure (up to about 10 GPa) at three temperatures (300, 160, and 110 K). The evolution with pressure and temperature of the optical conductivity shows…

Strongly Correlated Electrons · Physics 2013-07-08 L. Baldassarre , A. Perucchi , P. Postorino , S. Lupi , C. Marini , L. Malavasi , J. Jiang , J. D. Weiss , E. E. Hellstrom , I. Pallecchi , P. Dore

Superconductivity with transition temperature $T_c=1.7$ K has been reported in bilayer graphene [1,2]. The main factors, which may shed light on the mechanism of the formation of this superconductivity, are the following. Superconductivity…

Superconductivity · Physics 2018-06-22 G. E. Volovik

We compute the optical conductivity for an out-of-plane deformation in graphene using an approach based on solutions of the Dirac equation in curved space. Different examples of periodic deformations along one direction translates into an…

Mesoscale and Nanoscale Physics · Physics 2014-05-05 A. J. Chaves , T. Frederico , O. Oliveira , W. de Paula , M. C. Santos

We study the DC transport of finite graphene samples with random gap. Using Dirac fermions to describe the low-energy physics near the Dirac point, we employ a generalized Drude form for the conductivity. The latter is constant for a…

Mesoscale and Nanoscale Physics · Physics 2010-06-14 K. Ziegler , A. Sinner

We calculate the optical (cutoff >> frequency >> temperature) conductivity in clean graphene in the ultimate low-energy regime, when retardation effects of the electromagnetic interaction become important and when the full Lorentz symmetry…

Strongly Correlated Electrons · Physics 2013-06-12 Igor F. Herbut , Vieri Mastropietro

Exposure of highly oriented pyrolytic graphite to bromine vapor gives rise to in-plane charge conductivities which increase monotonically with intercalation time toward values (for ~6 at% Br) that are significantly higher than Cu at…

Materials Science · Physics 2013-05-29 S. Tongay , J. Hwang , D. B. Tanner , H. K. Pal , D. Maslov , A. F. Hebard

Intrinsic bilayer graphene is a gapless semimetal. Under the application of a bias field it becomes a semiconductor with a direct band gap that is proportional to the applied field. Under a layer-asymmetric strain (where the upper layer…

Mesoscale and Nanoscale Physics · Physics 2014-12-04 J. A. Crosse

Graphene is a mechanically robust 2D material promising for flexible optoelectronic applications. However, its electromagnetic properties under strain are experimentally poorly understood. Here we present the far-infrared transmission…

Mesoscale and Nanoscale Physics · Physics 2017-05-22 Manisha Chhikara , Iaroslav Gaponenko , Patrycja Paruch , Alexey. B. Kuzmenko

We theoretically revisit graphene transport properties as a function of carrier density, taking into account possible correlations in the spatial distribution of the Coulomb impurity disorder in the environment. We find that the charged…

Mesoscale and Nanoscale Physics · Physics 2011-10-06 Qiuzi Li , E. H. Hwang , E. Rossi , S. Das Sarma

For graphene (a Dirac material) it has been theoretically predicted and experimentally observed that DC resistivity is proportional to $ T^4$ when the temperature is much less than Bloch- Gr\"{u}neisen ($\Theta_{BG}$) temperature and T…

Strongly Correlated Electrons · Physics 2016-10-18 Luxmi Rani , Navinder Singh

Optical conductivity s(w) of PrRu4P12 has been studied under high pressure to 14 GPa, at low temperatures to 8 K, and at photon energies 12 meV-1.1 eV. The energy gap in s(w) at ambient pressure, caused by a metal-insulator transition due…

We develop a theory for the optical conductivity of doped multilayer graphene including the effects of electron-electron interactions. Applying the quantum kinetic formalism, we formulate a set of pseudospin Bloch equations that governs the…

Mesoscale and Nanoscale Physics · Physics 2018-04-03 Xiao Li , Wang-Kong Tse

In this paper, we develop a theory of edge effects in graphene for its applications to nanoantennas in the terahertz, infrared, and visible frequency ranges. Its characteristic feature is selfconsistence reached due the formulation in terms…

Mesoscale and Nanoscale Physics · Physics 2023-05-26 Tomer Berghaus , Touvia Miloh , Oded Gottlieb , Gregory Slepyan

We demonstrate that the plasmon frequency and Drude weight of the electron liquid in a doped graphene sheet are strongly renormalized by electron-electron interactions even in the long-wavelength limit. This effect is not captured by the…

Mesoscale and Nanoscale Physics · Physics 2011-07-19 Saeed H. Abedinpour , G. Vignale , A. Principi , Marco Polini , Wang-Kong Tse , A. H. MacDonald

We consider superconducting properties of a two-dimensional Dirac material such as graphene under strain that produces a flat band spectrum in the normal state. We show that in the superconducting state, such a model results in a highly…

Superconductivity · Physics 2016-06-22 V. J. Kauppila , F. Aikebaier , T. T. Heikkilä

Conductivity of a disorder-free intrinsic graphene is studied to the first order in the long-range Coulomb interaction and is found to be \sigma=\sigma_0(1+0.01 g), where 'g' is the dimensionless ("fine structure") coupling constant. The…

Mesoscale and Nanoscale Physics · Physics 2009-02-25 E. G. Mishchenko

We show that for graphene with any finite difference in the on-site energy between the two sub-lattices ($\Delta$), The optical absorption edge is determined by the $\Delta$. The universal conductance will be broken and the conductance near…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 Lei Chen , Zhongshui Ma , C. Zhang