DSpace Coleção:
http://www.repositorio.ufc.br/handle/riufc/170
Sun, 19 Jan 2020 15:02:24 GMT2020-01-19T15:02:24ZExplosive Electric Breakdown due to Conducting-Particle Deposition on an Insulating Substrate
http://www.repositorio.ufc.br/handle/riufc/49129
Título: Explosive Electric Breakdown due to Conducting-Particle Deposition on an Insulating Substrate
Autor(es): Oliveira, Claudio Lucas Nunes de; Araújo, Nuno Azevedo Machado de; Andrade Júnior, José Soares de; Herrmann, Hans Jürgen
Abstract: We introduce a theoretical model to investigate the electric breakdown of a substrate on which highly
conducting particles are adsorbed and desorbed with a probability that depends on the local electric field.
We find that, by tuning the relative strength q of this dependence, the breakdown can change from
continuous to explosive. Precisely, in the limit in which the adsorption probability is the same for any finite
voltage drop, we can map our model exactly onto the q-state Potts model and thus the transition to a jump
occurs at q ¼ 4. In another limit, where the adsorption probability becomes independent of the local field
strength, the traditional bond percolation model is recovered. Our model is thus an example of a possible
experimental realization exhibiting a truly discontinuous percolation transition.Wed, 01 Jan 2014 00:00:00 GMThttp://www.repositorio.ufc.br/handle/riufc/491292014-01-01T00:00:00ZEnhanced flow in small-world networks
http://www.repositorio.ufc.br/handle/riufc/49127
Título: Enhanced flow in small-world networks
Autor(es): Oliveira, Claudio Lucas Nunes de; Morais, Pablo Abreu de; Moreira, André Auto; Andrade Júnior, José Soares de
Abstract: The proper addition of shortcuts to a regular substrate can lead to the formation of a complex network
with a highly efficient structure for navigation [J. M. Kleinberg, Nature 406, 845 (2000)]. Here we show
that enhanced flow properties can also be observed in these small-world topologies. Precisely, our model is
a network built from an underlying regular lattice over which long-range connections are randomly added
according to the probability, Pij ∼ r−α
ij , where rij is the Manhattan distance between nodes i and j, and the
exponent α is a controlling parameter. The mean two-point global conductance of the system is computed
by considering that each link has a local conductance given by gij ∝ r−C
ij , where C determines the extent of
the geographical limitations (costs) on the long-range connections. Our results show that the best flow
conditions are obtained for C ¼ 0 with α ¼ 0, while for C ≫ 1 the overall conductance always increases
with α. For C ≈ 1, α ¼ d becomes the optimal exponent, where d is the topological dimension of the
substrate. Interestingly, this exponent is identical to the one obtained for optimal navigation in small-world
networks using decentralized algorithms.Wed, 01 Jan 2014 00:00:00 GMThttp://www.repositorio.ufc.br/handle/riufc/491272014-01-01T00:00:00ZMultiband tunneling in trilayer graphene
http://www.repositorio.ufc.br/handle/riufc/49077
Título: Multiband tunneling in trilayer graphene
Autor(es): Van Duppen, Ben; Sena, Silvia Helena Roberto de; Peeters, François Maria Leopold
Abstract: The electronic tunneling properties of the two stable forms of trilayer graphene (TLG), rhombohedral ABC
and Bernal ABA, are examined for p-n and p-n-p junctions as realized by using a single gate (SG) or a double
gate (DG). For the rhombohedral form, due to the chirality of the electrons, the Klein paradox is found at normal
incidence for SG devices, while at high-energy interband scattering between additional propagation modes can
occur. The electrons in Bernal ABA TLG can have a monolayer- or bilayer-like character when incident on a
SG device. Using a DG, however, both propagation modes will couple by breaking the mirror symmetry of the
system, which induces intermode scattering and resonances that depend on the width of the DG p-n-p junction.
For ABC TLG the DG opens up a band gap which suppresses Klein tunneling. The DG induces also an unexpected asymmetry in the tunneling angle for single-valley electrons.Tue, 01 Jan 2013 00:00:00 GMThttp://www.repositorio.ufc.br/handle/riufc/490772013-01-01T00:00:00ZFermi-energy-dependent structural deformation of chiral single-wall carbon nanotubes
http://www.repositorio.ufc.br/handle/riufc/44386
Título: Fermi-energy-dependent structural deformation of chiral single-wall carbon nanotubes
Autor(es): Vieira, Bruno Gondim de Melo; Barros, Eduardo Bedê; Verçosa, Daniel Gomes; Samsonidze, Georgy; Souza Filho, Antonio Gomes de; Dresselhaus, Mildred SpiewakWed, 01 Jan 2014 00:00:00 GMThttp://www.repositorio.ufc.br/handle/riufc/443862014-01-01T00:00:00Z