Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 27: Symposium “Graphene”

TT 27.5: Vortrag

Donnerstag, 29. März 2007, 15:50–16:15, H20

Scattering approach to disordered graphene — •Mikhail Titov — University of Konstanz, Theoretical Solid State Physics, Department of Physics, M703, D-78457 Konstanz, Germany

Low-energy charge excitations in graphene are described by the "relativistic" massless Dirac equation, which is behind many exotic transport phenomena observed in this material. The quasiparticle density of states in graphene vanishes at zero doping when the chemical potential coincides with the Dirac electron-hole degeneracy point. Nevertheless the experiments demonstrate that the conductivity at this point reaches a finite minimal value of the order of 4 e²/h. Based on the scattering approach to the charge transport we provide a comprehensive description of the observed behaviour, which relies on the universal quasiparticle tunneling. We investigate the role of different types of disorder and conclude from comparison with experimental data that existing graphene samples possess a strong potential disorder, which is smooth on atomic scales.