Encontrados 6 documentos, a visualizar página 1 de 1
Scattering by linear defects in graphene : a tight-binding approach
Rodrigues, J. N. B.; Peres, N. M. R.; Santos, J. M. B. Lopes dosWe develop an analytical scattering formalism for computing the transmittance through periodic defect lines within the tight-binding model of graphene. We first illustrate the method with a relatively simple case, the pentagon-only defect line. Afterwards, more complex defect lines are treated, namely the zz(558) and the zz(5757) ones. The formalism developed, only uses simple tight-binding concepts, reducing t...
Continuum model of the twisted bilayer
Santos, J. M. B. Lopes dos; Peres, N. M. R.; Castro Neto, A. H.The continuum model of the twisted graphene bilayer (Phys. Rev. Lett. 99, 256802, 2007) is extended to include all types of commensurate structures. The essential ingredient of the model, the Fourier components of the spatially modulated hopping amplitudes, can be calculated analytically, for any type of commensurate structures in the low twist angle limit. We show that the Fourier components that could give ri...
Scattering by linear defects in graphene : a continuum approach
Rodrigues, J. N. B.; Peres, N. M. R.; Santos, J. M. B. Lopes dosWe study the low-energy electronic transport across periodic extended defects in graphene. In the continuum low-energy limit, such defects act as infinitesimally thin stripes separating two regions where Dirac Hamiltonian governs the low-energy phenomena. The behavior of these systems is defined by the boundary condition imposed by the defect on the massless Dirac fermions. We demonstrate how this low-energy bo...
Coulomb drag and high resistivity behavior in double layer graphene
Peres, N. M. R.; Santos, J. M. B. Lopes dos; Castro Neto, A. H.We show that Coulomb drag in ultra-clean graphene double layers can be used for controlling the on/o ratio for current ow by tunning the external gate voltage. Hence, although graphene remains semi-metallic, the double layer graphene system can be tuned from conductive to a highly resistive state. We show that our results explain previous data of Coulomb drag in double layer graphene samples in disordered SiO...
Zigzag graphene nanoribbon edge reconstruction with stone-wales defects
Rodrigues, João N. B.; Gonçalves, P. A. D.; Rodrigues, N. F. G.; Ribeiro, R. M.; Santos, J. M. B. Lopes dos; Peres, N. M. R.In this paper, we study zigzag graphene nanoribbons with edges reconstructed with Stone-Wales defects, by means of an empirical (first-neighbor) tight-binding method, with parameters determined by ab initio calculations of very narrow ribbons. We explore the characteristics of the electronic band structure with a focus on the nature of edge states. Edge reconstruction allows the appearance of a new type of edge ...
Disorder induced localized states in graphene
Pereira, Vitor M.; Guinea, F.; Santos, J. M. B. Lopes dos; Peres, N. M. R.; Castro Neto, A. H.We consider the electronic structure near vacancies in the half-filled honeycomb lattice. It is shown that vacancies induce the formation of localized states. When particle-hole symmetry is broken, localized states become resonances close to the Fermi level. We also study the problem of a finite density of vacancies, obtaining the electronic density of states, and discussing the issue of electronic localization...
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