475 research outputs found
Thermal Rectification In Asymmetric Graphene Ribbons
In this paper, heat flux in graphene nano ribbons has been studied by using
molecular dynamics simulations. It is found that the heat flux runs
preferentially along the direction of decreasing width, which demonstrates
significant thermal rectification effect in the asymmetric graphene ribbons.
The dependence of rectification ratio on the vertex angle and the length are
also discussed. Compared to the carbon nanotube based one-dimensional thermal
rectifier, graphene nano ribbons have much higher rectification ratio even in
large scale. Our results demonstrate that asymmetric graphene ribbon might be a
promising structure for practical thermal (phononics) device
Magneto-transport through graphene nano-ribbons
We investigate magneto-transport through graphene nano-ribbons as a function
of gate and bias voltage, and temperature. We find that a magnetic field
systematically leads to an increase of the conductance on a scale of a few
tesla. This phenomenon is accompanied by a decrease in the energy scales
associated to charging effects, and to hopping processes probed by
temperature-dependent measurements. All the observations can be interpreted
consistently in terms of strong-localization effects caused by the large
disorder present, and exclude that the insulating state observed in
nano-ribbons can be explained solely in terms of a true gap between valence and
conduction band.Comment: 4 pages, 5 figure
Electrostatic confinement of electrons in graphene nano-ribbons
Coulomb blockade is observed in a graphene nanoribbon device with a top gate.
When two pn junctions are formed via the back gate and the local top gate,
electrons are confined between the pn junctions which act as the barriers. When
no pn junctions are induced by the gate voltages, electrons are still confined,
as a result of strong disorder, but in a larger area. Measurements on five
other devices with different dimensions yield consistent results.Comment: 4 figures, 1 table, 4.4page
Energy Controlled Edge Formation for Graphene Nano Ribbons
On the basis of first principles calculations, we report energy estimated to
cut a graphene sheet into nanoribbons of armchair and zigzag configurations.
Our calculations show that the energy required to cut a graphene sheet into
zigzag configuration is higher than that of armchair configuration by an order
of 0.174 eV. Thus, a control over the threshold energy might be helpful in
designing an experiment for cutting a graphene sheet into smooth edged armchair
or zigzag configurations
Transport properties in network models with perfectly conducting channels
We study the transport properties of disordered electron systems that contain
perfectly conducting channels. Two quantum network models that belong to
different universality classes, unitary and symplectic, are simulated
numerically. The perfectly conducting channel in the unitary class can be
realized in zigzag graphene nano-ribbons and that in the symplectic class is
known to appear in metallic carbon nanotubes. The existence of a perfectly
conducting channel leads to novel conductance distribution functions and a
shortening of the conductance decay length.Comment: 4 pages, 6 figures, proceedings of LT2
Multi-plasmon absorption in graphene
We show that graphene possesses a strong nonlinear optical response in the
form of multi-plasmon absorption, with exciting implications in classical and
quantum nonlinear optics. Specifically, we predict that graphene nano-ribbons
can be used as saturable absorbers with low saturation intensity in the
far-infrared and terahertz spectrum. Moreover, we predict that two-plasmon
absorption and extreme localization of plasmon fields in graphene nano-disks
can lead to a plasmon blockade effect, in which a single quantized plasmon
strongly suppresses the possibility of exciting a second plasmon
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