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Dirac-electronic tunneling and nonlinear transport properties with both finite and zero energy bandgap are investigated for graphene with a tilted potential barrier under a bias. For validation, results from a finite-difference based…

Mesoscale and Nanoscale Physics · Physics 2020-04-01 Farhana Anwar , Andrii Iurov , Danhong Huang , Godfrey Gumbs , Ashwani Sharma

We analyze the scattering sector of the Hamiltonians for both gapless and gapped graphene in the presence of a charge impurity using the 2D Dirac equation, which is applicable in the long wavelength limit. We show that for certain range of…

Mesoscale and Nanoscale Physics · Physics 2011-04-07 Kumar S. Gupta , Andjelo Samsarov , Siddhartha Sen

Graphene lacks an intrinsic band-gap, which limits its use in electronic applications. Here we demonstrate that periodic arrays of topological defects can open and control a band-gap in a predictable manner governed by defect spacing and…

Numerical simulations in a tight-binding model have shown that an intersection of topologically protected one-dimensional chiral channels can function as a beam splitter for non-interacting fermions on a two-dimensional lattice…

Other Condensed Matter · Physics 2017-02-08 J. R. Anglin , A. Schulz

The electrical conductivity of suspended graphene has recently been measured for the first time, and found to behave as \sigma ~ \sqrt{|n|} as expected for Dirac quasiparticles at large carrier density. The charge inhomogeneity is strongly…

Strongly Correlated Electrons · Physics 2016-08-14 Joaquín E. Drut , Timo A. Lähde , Eero Tölö

Graphene-based superlattice (SL) formed by a periodic gap modulation is studied theoretically using a Dirac-type Hamiltonian. Analyzing the dispersion relation we have found that new Dirac points arise in the electronic spectrum under…

Mesoscale and Nanoscale Physics · Physics 2015-06-11 G. M. Maksimova , E. S. Azarova , A. V. Telezhnikov , V. A. Burdov

A study of the formation of excitons as a problem of two Dirac particles confined in two-layer graphene sheets separated by a dielectric when gaps are opened and they interact via a Coulomb potential is presented. We propose to observe…

Mesoscale and Nanoscale Physics · Physics 2013-07-30 Oleg L. Berman , Roman Ya. Kezerashvili , Klaus G. Ziegler

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 existence and stability of Dirac nodal lines in three-dimensional layered systems, whose layers individually have Dirac nodal points protected by chiral (sublattice) symmetry. The model system we consider is the rhombohedral…

Mesoscale and Nanoscale Physics · Physics 2017-09-21 Ching-Hong Ho , Cheng-Peng Chang , Ming-Fa Lin

G. Cocco, E. Cadelano, and L. Colombo [Phys. Rev. B 81, 241412(R) (2010)] have suggested that combinations of shear and uniaxial strain can be used to open a band gap in graphene at much lower levels of strain than with the application of…

Materials Science · Physics 2010-08-02 Ashwin Ramasubramaniam

This review aims at a theoretical discussion of Dirac points in two-dimensional systems. Whereas Dirac points and Dirac fermions are prominent low-energy electrons in graphene (two-dimensional graphite), research on Dirac fermions in…

Mesoscale and Nanoscale Physics · Physics 2014-10-16 Mark O. Goerbig , Gilles Montambaux

We study the conditions for spontaneously generating an excitonic mass gap due to Coulomb interactions between anisotropic Dirac fermions in uniaxially strained graphene. The mass gap equation is realized as a self-consistent solution for…

Strongly Correlated Electrons · Physics 2017-06-15 Anand Sharma , Valeri N. Kotov , Antonio H. Castro Neto

The charge carrier density in graphene on a dielectric substrate such as SiO$_2$ displays inhomogeneities, the so-called charge puddles. Because of the linear dispersion relation in monolayer graphene, the puddles are predicted to grow near…

Mesoscale and Nanoscale Physics · Physics 2016-03-30 S. Samaddar , I. Yudhistira , S. Adam , H. Courtois , C. B. Winkelmann

BN domains are easy to form in the basal plane of graphene due to phase separation. With first-principles DFT calculations, it is demonstrated theoretically that the band gap of graphene can be opened effectively around K (or K') points by…

Materials Science · Physics 2010-12-23 X. F. Fan , Jer-lai Kuo , Z. X. Shen

The unusual transport properties of graphene are the direct consequence of a peculiar bandstructure near the Dirac point. We determine the shape of the pi bands and their characteristic splitting, and the transition from a pure 2D to…

Materials Science · Physics 2007-05-23 Taisuke Ohta , Aaron Bostwick , J. L. McChesney , Thomas Seyller , Karsten Horn , Eli Rotenberg

We present a description of the energy loss of a charged particle moving parallel to a graphene layer and graphene double layers. Specifically, we compare the stopping power of the plasma oscillations for these two configurations in the…

Materials Science · Physics 2015-05-28 Godfrey Gumbs , O. Roslyak , Danhong Huang , Antonios Balassis

It is known that fluctuations in the electrostatic potential allow for metallic conduction (nonzero conductivity in the limit of an infinite system) if the carriers form a single species of massless two-dimensional Dirac fermions. A nonzero…

Mesoscale and Nanoscale Physics · Physics 2013-07-09 J. H. Bardarson , M. V. Medvedyeva , J. Tworzydlo , A. R. Akhmerov , C. W. J. Beenakker

A moire pattern is formed when two copies of a periodic pattern are overlaid with a relative twist. We address the electronic structure of a twisted two-layer graphene system, showing that in its continuum Dirac model the moire pattern…

Mesoscale and Nanoscale Physics · Physics 2016-07-13 R. Bistritzer , A. H. MacDonald

The spectrum of tight binding electrons on a square lattice with half a magnetic flux quantum per unit cell exhibits two Dirac points at the band center. We show that, in the presence of an additional uniaxial staggered potential, this pair…

Mesoscale and Nanoscale Physics · Physics 2011-01-06 P. Delplace , G. Montambaux

The Dirac-like quasiparticles in honeycomb graphene lattice are taken to possess a non-zero effective mass. The charge carriers involve to interact with a femtosecond strong laser pulse. Due to the scattering time of electrons in graphene…

Mesoscale and Nanoscale Physics · Physics 2017-01-31 Z. Ahmadi , H. Goudarzi , A. Jafari
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