Abstract
The density of states and conductivity are calculated for scatterers with nonzero range in bilayer graphene within a self-consistent Born approximation. For scatterers with a Gaussian potential, the minimum conductivity at zero energy remains universal in the clean limit, but increases with disorder and becomes nonuniversal for long-range scatterers. For charged impurities, we use the Thomas–Fermi approximation for the screening effect. The minimum conductivity increases with impurity concentration but the dependence is not so considerable. When the excited conduction band starts to be populated by electrons, the conductivity increases due to the increase in the screening effect.
Highlights
Atomically thin graphenes consisting of a few layers of a monolayer graphite sheet were experimentally fabricated using mechanical exfoliation1,2) and epitaxial growth.3,4) Several reviews have already been published.5−8) Transport properties of graphenes were often studied in a self-consistent Born approximation assuming model short-range scatterers because of simplicity.9−15) Quite recently, calculations were extended to the case of long-range scatterers in monolayer graphene.16) The purpose of this paper is to study density of states and conductivity of bilayer graphene in the presence of scatterers with nonzero range
Various theoretical studies were reported on transport properties of bilayer graphene including those within a self-consistent Born approximation.12,14,24,29−31) In particular, the conductivity was shown to take at zero energy a universal value twice as large as that in monolayer graphene.12) In this paper, we extend selfconsistent Born approximation to the case of scatterers with nonzero range and calculate the density of states and the conductivity in this system
In order to see the explicit dependence on the potential range, we first assume scatterers with a Gaussian potential v(r) v0 πd[2] exp with range d
Summary
Atomically thin graphenes consisting of a few layers of a monolayer graphite sheet were experimentally fabricated using mechanical exfoliation1,2) and epitaxial growth.3,4) Several reviews have already been published.5−8) Transport properties of graphenes were often studied in a self-consistent Born approximation assuming model short-range scatterers because of simplicity.9−15) Quite recently, calculations were extended to the case of long-range scatterers in monolayer graphene.16) The purpose of this paper is to study density of states and conductivity of bilayer graphene in the presence of scatterers with nonzero range In graphenes, their electronic structure strongly varies with the change in the number of layers.
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