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The strong Coulomb interaction between massless Dirac fermions can drive a semimetal-insulator transition in single-layer graphene by dynamically generating an excitonic fermion gap. There is a critical interaction strength $\lambda_c$ that…

Strongly Correlated Electrons · Physics 2015-03-13 Wei Li , Guo-Zhu Liu

It is argued that the specific heat of $N$ massless Dirac fermions in 2 spatial dimensions interacting with 1/r Coulomb interactions is suppressed logarithmically relative to its non-interacting counterpart. The (dimensionless) coefficient…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Oskar Vafek

We present extensive numerical results for the thermodynamic density of states (i.e. quantum capacitance) of a two-dimensional massless Dirac fermion fluid in a doped graphene sheet. In particular, by employing the random phase…

Mesoscale and Nanoscale Physics · Physics 2014-10-23 Reza Asgari , Mikhail I. Katsnelson , Marco Polini

Materials with massless Dirac fermions can possess exceptionally strong and widely tunable optical nonlinearities. Experiments on graphene monolayer have indeed found very large third-order nonlinear responses, but the reported variation of…

Motivated by recent graphene transport experiments, we have undertaken a numerical study of the conductivity of disordered two-dimensional massless Dirac fermions. Our results reveal distinct differences between the cases of short-range and…

Mesoscale and Nanoscale Physics · Physics 2008-06-30 Kentaro Nomura , A. H. MacDonald

Pristine monolayer graphene exhibits very poor screening because the density of states vanishes at the Dirac point. As a result, charge relaxation is controlled by the effects of zero-point motion (rather than by the Coulomb interaction)…

Mesoscale and Nanoscale Physics · Physics 2017-01-25 Eugene B. Kolomeisky , Joseph P. Straley

We compute the Coulomb correction $\mathcal{C}$ to the a. c. conductivity of interacting massless Dirac particles in graphene in the collisionless limit using the polarization tensor approach in a regularization independent framework.…

Mesoscale and Nanoscale Physics · Physics 2013-11-11 G. Gazzola , A. L. Cherchiglia , L. A. Cabral , M. C. Nemes , Marcos Sampaio

We consider a noncommutative description of graphene. This description consists of a Dirac equation for massless Dirac fermions plus noncommutative corrections, which are treated in the presence of an external magnetic field. We argue that,…

High Energy Physics - Theory · Physics 2014-01-16 C. Bastos , O. Bertolami , N. Dias , J. Prata

The impact of the electron-electron Coulomb interaction on the optical conductivity of graphene has led to a controversy that calls into question the universality of collisionless transport in this and other Dirac materials. Using a lattice…

Strongly Correlated Electrons · Physics 2016-07-06 Julia M. Link , Peter P. Orth , Daniel E. Sheehy , Jörg Schmalian

We theoretically design a graphene-based all-organic ferromagnetic semiconductor by terminating zigzag graphene nanoribbons (ZGNRs) with organic magnets. A large spin-split gap with 100% spin polarized density of states near the Fermi…

Materials Science · Physics 2017-09-13 D. Hou , J. H. Wei , S. J. Xie

The electrodynamics of a two-dimensional gas of massless fermions in graphene is studied by a collisionless hydrodynamic approach. A low-energy dispersion relation for the collective modes (plasmons) is derived both in the absence and in…

Mesoscale and Nanoscale Physics · Physics 2013-12-10 R. Roldán , J. -N. Fuchs , M. O. Goerbig

Effects of the spin-orbit interactions on the energy spectrum, Fermi surface and spin dynamics are studied in structural- and bulk-inversion asymmetric quasi-two-dimensional structures with a finite thickness in the presence of a parabolic…

Mesoscale and Nanoscale Physics · Physics 2015-03-19 E. Nakhmedov , O. Alekperov , R. Oppermann

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

At low energies, electrons in doped graphene sheets are described by a massless Dirac fermion Hamiltonian. In this work we present a semi-analytical expression for the dynamical density-density linear-response function of noninteracting…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 M. R. Ramezanali , M. M. Vazifeh , Reza Asgari , Marco Polini , A. H. MacDonald

The density of states (DOS) of graphene underneath a metal is estimated through a quantum capacitance measurement of the metal/graphene/SiO2/n+-Si contact structure fabricated by a resist-free metal deposition process. Graphene underneath…

Materials Science · Physics 2013-07-22 Ryota Ifuku , Kosuke Nagashio , Tomonori Nishimura , Akira Toriumi

In a clean Fermi liquid, due to spin up/spin down symmetry, the dc spin current driven by a magnetic field gradient is finite even in the absence of impurities. Hence, the spin conductivity sigma_s assumes a well-defined collision-dominated…

Strongly Correlated Electrons · Physics 2015-05-20 Markus Mueller , Hai Chau Nguyen

The electron-electron interactions effects on the shape of the Fermi surface of doped graphene are investigated. The actual discrete nature of the lattice is fully taken into account. A $\pi$-band tight-binding model, with nearest-neighbor…

Strongly Correlated Electrons · Physics 2008-03-14 R. Roldan , M. P. Lopez-Sancho , F. Guinea

In neutral graphene dots the Fermi level coincides with the Dirac points. We have investigated in the presence of a magnetic field several unusual properties of single electron states near the Fermi level of such a rectangular-shaped…

Mesoscale and Nanoscale Physics · Physics 2010-02-24 S. C. Kim , P. S. Park , S. -R. Eric Yang

The different physical properties of multilayered graphene or graphite relative to single layer graphene result from the Dirac spins symmetry in graphene and the Pauli spin symmetry in graphite. The Dirac symmetry in multilayers of graphene…

Materials Science · Physics 2011-10-28 Reginald B. Little , Glenn J. Gex , Muhammad Ansari , James W. Mitchell

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