26,013 research outputs found
Sublattice asymmetry of impurity doping in graphene: A review
In this review we highlight recent theoretical and experimental work on
sublattice asymmetric doping of impurities in graphene, with a focus on
substitutional Nitrogen dopants. It is well known that one current limitation
of graphene in regards to its use in electronics is that in its ordinary state
it exhibits no band gap. By doping one of its two sublattices preferentially it
is possible to not only open such a gap, which can furthermore be tuned through
control of the dopant concentration, but in theory produce quasi-ballistic
transport of electrons in the undoped sublattice, both important qualities for
any graphene device to be used competetively in future technology. We outline
current experimental techniques for synthesis of such graphene monolayers and
detail theoretical efforts to explain the mechanisms responsible for the
effect, before suggesting future research directions in this nascent field.Comment: 20 pages, 4 figures. Accepted for publication in Beilstein Journal of
Nanotechnolog
Tunable plasmonic enhancement of light scattering and absorption in graphene-coated subwavelength wires
The electromagnetic response of subwavelength wires coated with a graphene
monolayer illuminated by a linearly polarized plane waves is investigated. The
results show that the scattering and extintion cross-sections of the coated
wire can be dramatically enhanced when the incident radiation resonantly
excites localized surface plasmons. The enhancements occur for p--polarized
incident waves and for excitation frequencies that correspond to complex poles
in the coefficients of the multipole expansion for the scattered field. By
dynamically tuning the chemical potential of graphene, the spectral position of
the enhancements can be chosen over a wide range.Comment: Accepted for publication in Journal of Optics 201
Majorana and the theoretical problem of photon-electron scattering
Relevant contributions by Majorana regarding Compton scattering off free or
bound electrons are considered in detail, where a (full quantum) generalization
of the Kramers-Heisenberg dispersion formula is derived. The role of
intermediate electronic states is appropriately pointed out in recovering the
standard Klein-Nishina formula (for free electron scattering) by making
recourse to a limpid physical scheme alternative to the (then unknown) Feynman
diagram approach. For bound electron scattering, a quantitative description of
the broadening of the Compton line was obtained for the first time by
introducing a finite mean life for the excited state of the electron system.
Finally, a generalization aimed to describe Compton scattering assisted by a
non-vanishing applied magnetic field is as well considered, revealing its
relevance for present day research.Comment: latex, amsart, 10 pages, 1 figur
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