78,132 research outputs found
Tuning electronic structure of graphene via tailoring structure: theoretical study
Electronic structures of graphene sheet with different defective patterns are
investigated, based on the first principles calculations. We find that
defective patterns can tune the electronic structures of the graphene
significantly. Triangle patterns give rise to strongly localized states near
the Fermi level, and hexagonal patterns open up band gaps in the systems. In
addition, rectangular patterns, which feature networks of graphene nanoribbons
with either zigzag or armchair edges, exhibit semiconducting behaviors, where
the band gap has an evident dependence on the width of the nanoribbons. For the
networks of the graphene nanoribbons, some special channels for electronic
transport are predicted.Comment: 5 figures, 6 page
New Parametrization of Neutrino Mixing Matrix
Global fits to neutrino oscillation data are compatible with tri-bimaximal
mixing pattern, which predicts and . We propose here to
parametrize the tri-bimaximal mixing matrix by its hermitian
generator using the exponential map. Then we use the exponential map
to express the deviations from tri-bimaximal pattern by deriving the hermitian
matrices and . These deviations might come from the symmetry
breaking of the neutrino and charged lepton sectors.Comment: 10 pages, no figures, correted minor typo
Extrinsic models for the dielectric response of CaCu{3}Ti{4}O{12}
The large, temperature-independent, low-frequency dielectric constant
recently observed in single-crystal CaCu{3}Ti{4}O{12} is most plausibly
interpreted as arising from spatial inhomogenities of its local dielectric
response. Probable sources of inhomogeneity are the various domain boundaries
endemic in such materials: twin, Ca-ordering, and antiphase boundaries. The
material in and neighboring such boundaries can be insulating or conducting. We
construct a decision tree for the resulting six possible morphologies, and
derive or present expressions for the dielectric constant for models of each
morphology. We conclude that all six morphologies can yield dielectric behavior
consistent with observations and suggest further experiments to distinguish
among them.Comment: 9 pages, with 1 postscript figure embedded. Uses REVTEX and epsf
macros. Also available at
http://www.physics.rutgers.edu/~dhv/preprints/mc_ext/index.htm
Mathematical control of complex systems 2013
Mathematical control of complex systems have already become an ideal research area for control engineers, mathematicians, computer scientists, and biologists to understand, manage, analyze, and interpret functional information/dynamical behaviours from real-world complex dynamical systems, such as communication systems, process control, environmental systems, intelligent manufacturing systems, transportation systems, and structural systems. This special issue aims to bring together the latest/innovative knowledge and advances in mathematics for handling complex systems. Topics include, but are not limited to the following: control systems theory (behavioural systems, networked control systems, delay systems, distributed systems, infinite-dimensional systems, and positive systems); networked control (channel capacity constraints, control over communication networks, distributed filtering and control, information theory and control, and sensor networks); and stochastic systems (nonlinear filtering, nonparametric methods, particle filtering, partial identification, stochastic control, stochastic realization, system identification)
Filamentary superconductivity across the phase diagram of Ba(Fe,Co)As
We show magnetotransport results on Ba(FeCo)As () single crystals. We identify the low temperature resistance step
at 23 K in the parent compound with the onset of filamentary superconductivity
(FLSC), which is suppressed by an applied magnetic field in a similar manner to
the suppression of bulk superconductivity (SC) in doped samples. FLSC is found
to persist across the phase diagram until the long range antiferromagnetic
order is completely suppressed. A significant suppression of FLSC occurs for
, the doping concentration where bulk SC emerges. Based on these
results and the recent report of an electronic anisotropy maximum for 0.02
0.04 [Science 329, 824 (2010)], we speculate that, besides spin
fluctuations, orbital fluctuations may also play an important role in the
emergence of SC in iron-based superconductors.Comment: 5 pages, 3 figure
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