Results for "Minos A. Neto"

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Phase diagrams of the transverse Ising antiferromagnet in the presence of the longitudinal magnetic fieldJul 09 2012In this paper we study the critical behavior of the two-dimensional antiferromagnetic Ising model in both uniform longitudinal ($H$) and transverse ($\Omega $) magnetic fields. Using the effective-field theory (EFT) with correlation in single site cluster ... More
A mean-field approach applied for the ferromagnetic spin-1 Blume-Capel modelJul 05 2016We applied a mean-field approach associated to Monte Carlo simulations in order to study the spin-1 ferromagnetic Blume-Capel model in the square and the linear lattice. This new technique, which we call MFT-MC, determines the molecular field as the magnetization ... More
Magnetization plateaus in the antiferromagnetic Ising chain with single-ion anisotropy and quenched disorderMay 15 2015We have studied the presence of plateaus on the low-temperature magnetization of an antiferromagnetic spin-1 chain, as an external uniform magnetic field is varied. A crystal-field interaction is present in the model and the exchange constants follow ... More
Multicritical behavior of the two-dimensional transverse Ising metamagnet in a longitudinal magnetic fieldJul 13 2016Magnetic phenomena of the superantiferromagnetic Ising model in both uniform longitudinal ($H$) and transverse ($\Omega $) magnetic fields are studied by employing a mean-field variational approach based on Peierls-Bogoliubov inequality for the free energy. ... More
The Rubber Band Revisited: Wang-Landau SimulationJul 09 2012In this work we apply Wang-Landau simulations to a simple model which has exact solutions both in the microcanonical and canonical formalisms. The simulations were carried out by using an updated version of the Wang-Landau sampling. We consider a homopolymer ... More
The magnetic susceptibility on the transverse antiferromagnetic Ising model: Analysis of the reentrant behaviourMay 19 2016We study the three-dimensional antiferromagnetic Ising model in both uniform longitudinal ($H$) and transverse ($\Omega $) magnetic fields by using the effective-field theory with finite cluster $N=1$ spin (EFT-1). We analyzed the behavior of the magnetic ... More
Thermodynamic properties of rod-like chains: entropic sampling simulationsMay 17 2016In this work we apply entropic sampling simulations to a three-state model which has exact solutions in the microcanonical and grand-canonical ensembles. We consider $N$ chains placed on an unidimensional lattice, such that each site may assume one of ... More
The Ising antiferromagnet on an anisotropic simple cubic lattice in the presence of a magnetic fieldJun 27 2012We have studied the anisotropic three-dimensional nearest-neighbor Ising model with competitive interactions in an uniform longitudinal magnetic field $H$. The model consists of ferromagnetic interaction $J_{x}(J_{z})$ in the $x(z)$ direction and antiferromagnetic ... More
Tuning the generalized Hybrid Monte Carlo algorithmSep 14 1995We discuss the analytic computation of autocorrelation functions for the generalized Hybrid Monte Carlo algorithm applied to free field theory and compare the results with numerical results for the $O(4)$ spin model in two dimensions. We explain how the ... More
An individual based model with global competition interaction: fluctuations effects in pattern formationApr 02 2007Feb 27 2008We present some numerical results obtained from a simple individual based model that describes clustering of organisms caused by competition. Our aim is to show how, even when a deterministic description developed for continuum models predicts no pattern ... More
Entropy of polydisperse chains: solution on the Bethe latticeMar 04 2008May 21 2008We consider the entropy of polydisperse chains placed on a lattice. In particular, we study a model for equilibrium polymerization, where the polydispersivity is determined by two activities, for internal and endpoint monomers of a chain. We solve the ... More
Entropy of polydisperse chains: solution on the Husimi latticeSep 27 2012Jan 09 2013We consider the entropy of polydisperse chains placed on a lattice. In particular, we study a model for equilibrium polymerization, where the polydispersivity is determined by two activities, for internal and endpoint monomers of a chain. We solve the ... More
Cooper-pair size and binding energy for unconventional superconducting systemsJan 16 2018The main proposal of this paper is to analyze the size of the Cooper pairs composed by unbalanced mass fermions from different electronic bands along the BCS-BEC crossover and study the binding energy of the pairs. We are considering an interaction between ... More
Bosonic Dirac Materials on a honeycomb antiferromagnetic Ising modelApr 12 2019Motivated by the recent proposal of Bosonic Dirac materials (BDM), we revisited the Ising model on a honeycomb lattice in the presence of the longitudinal and transverse fields. We apply linear spin-wave theory to obtain the magnon dispersion and its ... More
A Tale of Two Theories: Quantum Griffiths Effects in Metallic SystemsNov 08 2004We show that two apparently contradictory theories on the existence of Griffiths-McCoy singularities in magnetic metallic systems [1,2] are in fact mathematically equivalent. We discuss the generic phase diagram of the problem and show that there is a ... More
N=2-Supersymmetric Dynamics of a Spin-1/2 Particle in an Extended External FieldApr 25 2002Apr 25 2002One considers the quantum dynamics of a charged spin-1/2 particle in an extended external eletromagnetic field that arises from the reduction of a 5-dimensional Abelian gauge theory. The non-relativistic regime of the reduced 4D-dynamics is worked out ... More
Photon Mass and Very Long Baseline InterferometryDec 10 2010A relation between the photon mass, its frequency, $\nu$, and the deflection parameter, $\gamma$, determined by experimentalists (which characterizes the contribution of space curvature to gravitational deflection) is found. This amazing result allows ... More
Physical Variables of $d=3$ Maxwell-Chern-Simons Theory by Symplectic Projector MethodJul 16 2004Jul 31 2004The Symplectic Projector Method is applied to derive the local physical degrees of freedom and the physical Hamiltonian of the Maxwell-Chern-Simons theory in $d=1+2$. The results agree with the ones obtained in the literature through different approaches. ... More
First-principles Calculation of the Single Impurity Surface Kondo ResonanceDec 19 2005Oct 12 2006We have performed first-principles calculation of the surface and bulk wavefunctions of the Cu(111) surface and their hybridization energies to a Co adatom, including the potential scattering from the Co. By analyzing the calculated hybridization energies, ... More
Vacancies and oxidation of 2D group-IV monochalcogenidesApr 14 2016Point defects in the binary group-IV monochalcogenide monolayers of SnS, SnSe, GeS, GeSe are investigated using density-functional-theory calculations. Several stable configurations are found for oxygen defects, however we give evidence that these materials ... More
Enhanced piezoelectricity and modified dielectric screening of 2-D group-IV monochalcogenidesNov 05 2015We use first principles calculations to investigate the lattice properties of group-IV monochalcogenides. These include static dielectric permittivity, elastic and piezoelectric tensors. For the monolayer, it is found that the static permittivity, besides ... More
Phonons and Solitons in 1D Mott InsulatorsOct 31 2000We study the problem of one-dimensional (1D) Luttinger liquids in the insulating Mott-Hubbard phase in the presence of acoustic phonons in the semiclassical limit. We show that solitonic excitations can propagate freely in the system and the energy required ... More
Effect of external conditions on the structure of scrolled graphene edgesFeb 18 2010Apr 12 2010Characteristic dimensions of carbon nanoscrolls - "buckyrolls" - are calculated by analyzing the competition between elastic, van der Waals, and electrostatic energies for representative models of suspended and substrate-deposited graphene samples. The ... More
Born-Infeld Electrodynamics and Euler-Heisenberg-like Model: outstanding examples of the lack of commutativity among quantized truncated actions and truncated quantized actionsDec 11 2009Oct 19 2010We calculate the lowest-order corrections to the static potential for both the generalized Born-Infeld Electrodynamics and an Euler-Heisenberg-like model, in the presence of a constant external magnetic field. Our analysis is carried out within the framework ... More
Lenosky's energy and the phonon dispersion of grapheneJun 09 2009Jul 07 2009We calculate the phonon spectrum for a graphene sheet resulting from the model proposed by T. Lenosky et al. (Nature 355, 333 (1992)) for the free energy of the lattice. This model takes into account not only the usual bond bending and stretching terms, ... More
Physics Beyond the Standard Model: Focusing on the Muon AnomalyOct 27 2004May 14 2006We present a model based on the implication of an exceptional E_{6}-GUT symmetry for the anomalous magnetic moment of the muon. We follow a particular chain of breakings with Higgses in the 78 and 351 representations. We analyse the radiative correction ... More
A new analytical expression for Fowler-Nordheim current densityAug 15 2014Field emission from metallic emitters is generally described by the Fowler-Nordheim equation. The standard Fowler-Nordheim formula is expressed in terms of elliptic integrals which are not easy to extract a physical interpretation. In this work a single ... More
A new effective-field technique for the ferromagnetic spin-1 Blume-Capel model in a transverse crystal fieldJun 11 2017A new approximating technique is developed so as to study the quantum ferromagnetic spin-1 Blume-Capel model in the presence of a transverse crystal field in the square lattice. Our proposal consists of approaching the spin system by considering islands ... More
Electrically Detected Magnetic Resonance Modeling and Fitting: An Equivalent Circuit ApproachJul 03 2013Continuous-wave electrically detected magnetic resonance (cw-EDMR or just EDMR) and its variants are powerful tools to investigate spin-dependent processes in materials and devices. The use of quadrature detection improves the quality and selectivity ... More
Topics in Light Hadron Mass Spectrum in Quenched QCDAug 28 1996Aug 30 1996Several topics concerning the light hadron spectrum are discussed. Flavor symmetry breaking effects and the problem of quenched chiral logarithm are examined with pion mass data for the Kogut-Susskind quark action, and light meson decay constants for ... More
Results from the MINOS Experiment and New MINOS+ DataJul 30 2015The MINOS experiment took data for seven years between May 2005 and April 2012. Since then it has been reborn as the new MINOS+ experiment in the upgraded medium energy NuMI beam and started taking data in September 2013. An update to the MINOS standard ... More
Mobility of Bloch Walls via the Collective Coordinate MethodFeb 25 1999We have studied the problem of the dissipative motion of Bloch walls considering a totally anisotropic one dimensional spin chain in the presence of a magnetic field. Using the so-called "collective coordinate method" we construct an effective Hamiltonian ... More
Spin-1/2 anisotropic Heisenberg antiferromagnet with Dzyaloshinskii-Moriya interaction via mean-field approximationFeb 20 2018The spin-1/2 anisotropic Heisenberg model with antiferromagnetic exchange interactions in the presence of a external magnetic field and a Dzyaloshinskii-Moriya interaction is studied by employing the usual mean-field approximation. The magnetic properties ... More
The quantum cat map on the modular discretization of extremal black hole horizonsAug 28 2016May 29 2018Based on our recent work on the discretization of the radial AdS$_2$ geometry of extremal BH horizons,we present a toy model for the chaotic unitary evolution of infalling single particle wave packets. We construct explicitly the eigenstates and eigenvalues ... More
The Omega-Infinity Limit of Single SpikesNov 11 2015Apr 19 2016A new infinite-size limit of strings in RxS2 is presented. The limit is obtained from single spike strings by letting by letting the angular velocity parameter omega become infinite. We derive the energy-momenta relation of omega-infinity single spikes ... More
Neutrino Oscillation Studies with MINOSOct 20 2008The MINOS experiment observes the NuMI beam produced by the Main Injector accelerator at two detector stations, one 1 km and the other 735 km from the neutrino production target. From the disappearance of neutrinos in flight between the two detectors, ... More
An Approach for Reviewing Security-Related Aspects in Agile Requirements Specifications of Web ApplicationsJun 27 2019Defects in requirements specifications can have severe consequences during the software development lifecycle. Some of them result in overall project failure due to incorrect or missing quality characteristics such as security. There are several concerns ... More
Oxygen defects in phosphoreneJul 22 2014Aug 14 2014Oxygen, invariably present in a normal working environment, is a fundamental cause of the degradation of phosphorene. Using first-principles calculations, we show that for each oxygen atom adsorbed onto phosphorene there is an energy release of about ... More
Phase transition induced for external field in tree-dimensional isotropic Heisenberg antiferromagnetJun 22 2017In this paper, we report mean-field and effective-field renormalization group calculations on the isotropic Heisenberg antiferromagnetic model under a longitudinal magnetic field. As is already known, these methods, denoted by MFRG and EFRG, are based ... More
Qualitative aspects of the phase diagram of J1-J2 model on the cubic latticeAug 27 2012Jul 17 2013The qualitative aspects of the phase diagram of the Ising model on the cubic lattice, with ferromagnetic nearest-neighbor interactions ($J_{1}$) and antiferromagnetic next-nearest-neighbor couplings ($J_{2}$) are analyzed in the plane temperature versus ... More
Valleytronics in Tin (II) SulfideAug 31 2015Tin (II) sulfide (SnS) is a layered mineral found in nature. In this paper, we study the two-dimensional form of this material using a combination of \emph{ab initio} calculation and $\mathbf{k}\cdot\mathbf{p}$ theory. In particular, we address the valley ... More
New class of spin projection operators for 3D modelsJul 19 2012Dec 03 2012A new set of projection operators for three-dimensional models are constructed. Using these operators, an uncomplicated and easily handling algorithm for analysing the unitarity of the aforementioned systems is built up. Interestingly enough, this method ... More
Probing singularities in quantum cosmology with curvature scalarsAug 28 2007Mar 10 2010We provide further evidence that the canonical quantization of cosmological models eliminates the classical Big Bang singularity, using the {\it DeBroglie-Bohm} interpretation of quantum mechanics. The usual criterion for absence of the Big Bang singularity ... More
The spin-3/2 Blume-Capel model with competing short- and long-range interactionsFeb 20 2016The phase diagrams of the spin-$3/2$ Blume-Capel model with competing short and long-range interactions were studied through the free energy density obtained by analytical methods. The competition emerges when positive short-range interactions of strength ... More
Condensation of Vortex-Strings: Effective Potential Contribution Through Dual ActionsApr 09 2007Topological excitations are believed to play an important role in different areas of physics. For example, one case of topical interest is the use of dual models of quantum cromodynamics to understand properties of its vacuum and confinement through the ... More
Angular Momentum of the BTZ Black Hole in the Teleparallel GeometryApr 18 2005May 19 2005We carry out the Hamiltonian formulation of the three- dimensional gravitational teleparallelism without imposing the time gauge condition, by rigorously performing the Legendre transform. Definition of the gravitational angular momentum arises by suitably ... More
Casimir Effect at finite temperature for the Kalb-Ramond fieldDec 01 2010We use the thermofield dynamics (TFD) formalism to obtain the energy-momentum tensor for the Kalb-Ramond (KR) field in a topology $% S^{1}\times S^{1}\times R^{2}$. The compactification is carried out by a generalized TFD-Bogoliubov transformation that ... More
Optimizing optical tweezing with directional scattering in composite microspheresJun 19 2018Trapping of microspheres with a single focused laser beam is usually limited to materials with relative refractive indexes slightly larger than one. We show that directional light scattering can be employed to optically trap high-index materials. For ... More
Strain-induced gauge and Rashba fields in ferroelectric Rashba lead chalcogenide PbX monolayers (X = S, Se, Te)Jun 28 2018One of the exciting features of two-dimensional (2D) materials is their electronic and optical tunability through strain engineering. Previously, we found a class of 2D ferroelectric Rashba semiconductors PbX (X = S, Se, Te) with tunable spin-orbital ... More
Charge ordering and long-range interactions in layered transition metal oxidesMay 27 1998We study the competition between long-range and short-range interactions among holes within the spin density wave picture of layered transition metal oxides. We focus on the problem of charge ordering and the charge phase diagram. We show that the main ... More
How hole defects modify vortex dynamics in ferromagnetic nanodisksSep 11 2008Defects introduced in ferromagnetic nanodisks may deeply affect the structure and dynamics of stable vortex-like magnetization. Here, analytical techniques are used for studying, among other dynamical aspects, how a small cylindrical cavity modify the ... More
An Early Universe Model with Stiff Matter and a Cosmological ConstantJun 20 2011Nov 03 2011In the present work, we study the quantum cosmology description of a Friedmann-Robertson-Walker model in the presence of a stiff matter perfect fluid and a negative cosmological constant. We work in the Schutz's variational formalism and the spatial sections ... More
$p+^{4,6,8}He elastic scattering at intermediate energiesDec 02 2002Using a relativistic nuclear optical potential consisting of a Lorentz scalar, $V_{s}$, and the time-like component of a four-vector potential, $V_{0}$, we calculate elastic scattering differential cross sections and polarizations for $p+^{4}$He at intermediate ... More
On the Index of Constant Mean Curvature HypersurfacesJan 28 2009In 1968, Simons introduced the concept of index for hypersurfaces immersed into the Euclidean sphere S^{n+1}. Intuitively, the index measures the number of independent directions in which a given hypersurface fails to minimize area. The earliest results ... More
The Planck era with a negative cosmological constant and cosmic stringsJun 05 2010In the present letter, we consider the DeBroglie-Bohm interpretation of quantum Friedmann-Robertson-Walker models in the presence of a negative cosmological constant and cosmic strings. We compute the Bohm's trajectories and quantum potentials for a quantity ... More
Canonical transformation for stiff matter models in quantum cosmologyOct 22 2010In the present work we consider Friedmann-Robertson-Walker models in the presence of a stiff matter perfect fluid and a cosmological constant. We write the superhamiltonian of these models using the Schutz's variational formalism. We notice that the resulting ... More
Cold Black Holes in the Einstein-Scalar Field SystemApr 11 2006We study Einstein gravity coupled to a massless scalar field in a static spherically symmetric space-time in four dimensions. Black hole solutions exist when the kinetic energy of the scalar field is negative, that is, for a phantom field. These ``scalar ... More
Comments on Topologically Massive Gravity with Propagating TorsionMar 15 1999Jul 09 1999We study and discuss some of the consequences of the inclusion of torsion in 3D Einstein-Chern-Simons gravity. Torsion may trigger the excitation of non-physical modes in the spectrum. Higher-derivative terms are then added up and tree-level unitarity ... More
Continuum Model of the Twisted BilayerFeb 06 2012The continuum model of the twisted graphene bilayer (Phys. Rev. Lett. 99, 256802, 2007) is extended to include all types of commensurate structures. The essential ingredient of the model, the Fourier components of the spatially modulated hopping amplitudes, ... More
The Double Exchange Model at Low DensitiesMay 30 2005We obtain the phase diagram of the double-exchange model at low electronic densities in the presence of electron-electron interactions. The single particle problem and its extension to low electronic densities, when a Wigner crystal of magnetic polarons ... More
Double Exchange Model for Magnetic HexaboridesFeb 27 2004A microscopic theory for rare-earth ferromagnetic hexaborides, such as Eu(1-x)Ca(x)B6, is proposed on the basis of the double-exchange Hamiltonian. In these systems, the reduced carrier concentrations place the Fermi level near the mobility edge, introduced ... More
Cancellations for Circle-valued Morse Functions via Spectral SequencesOct 27 2016In this article, a spectral sequence analysis of a filtered Novikov complex $(\mathcal{N}_{\ast}(f),\Delta)$ over $\mathbb{Z}((t))$ is developed with the goal of obtaining results relating the algebraic and dynamical settings. Specifically, the unfolding ... More
Classical Solutions in a Lorentz-violating Maxwell-Chern-Simons ElectrodynamicsJan 28 2003We take as starting point the planar model arising from the dimensional reduction of the Maxwell Electrodynamics with the (Lorentz-violating) Carroll-Field-Jackiw term. We then write and study the extended Maxwell equations and the corresponding wave ... More
Hořava-Lifshitz cosmological models in noncommutative space-timesMay 23 2018In this work, we will analyze a noncommutative (NC) version of the Friedmann-Robert-Walker cosmological models within the gravitational Ho\v{r}ava-Lifshitz theory. The matter content of the models is described by a perfect fluid and the constant curvature ... More
Mean Field study of the heavy fermion metamagnetic transitionNov 13 2007Mar 31 2008We investigate the evolution of the heavy fermion ground state under application of a strong external magnetic field. We present a richer version of the usual hybridization mean field theory that allows for hybridization in both the singlet and triplet ... More
Retardation effects in the Holstein-Hubbard chain at half-fillingJul 26 2006Oct 16 2006The ground state phase diagram of the half-filled one-dimensional Holstein-Hubbard model contains a charge-density-wave (CDW) phase, driven by the electron-phonon (e-ph) coupling, and a spin-density-wave (SDW) phase, driven by the on-site electron-electron ... More
Renormalization-group approach to superconductivity: from weak to strong electron-phonon couplingMay 17 2005We present the numerical solution of the renormalization group (RG) equations derived in Ref. [1], for the problem of superconductivity in the presence of both electron-electron and electron-phonon coupling at zero temperature. We study the instability ... More
Electron-Electron Bound States in Maxwell-Chern-Simons-Proca QED3Dec 23 2002Jan 12 2005We start from a parity-breaking MCS QED$_{3}$ model with spontaneous breaking of the gauge symmetry as a framework for evaluation of the electron-electron interaction potential and for attainment of numerical values for the e-e bound state. Three expressions ... More
Non-Minimal Coupling to a Lorentz-Violating Background and Topological ImplicationsOct 10 2004Feb 22 2005The non-minimal coupling of fermions to a background responsible for the breaking of Lorentz symmetry is introduced in Dirac's equation; the non-relativistic regime is contemplated, and the Pauli's equation is used to show how an Aharonov-Casher phase ... More
Electron-electron attractive interaction in Maxwell-Chern-Simons QED3 at zero temperatureApr 12 2001One discusses the issue of low-energy electron-electron bound states in the Maxwell-Chern-Simons model coupled to QED3 with spontaneous breaking of a local U(1)-symmetry. The scattering potential, in the non-relativistic limit, steaming from the electron-electron ... More
Discommensuration-enhanced superconductivity in the charge density wave phases of transition-metal dichalcogenidesJun 21 2018Mar 19 2019We introduce a McMillan-Ginzburg-Landau theory to describe the cooperative coexistence of charge-density and superconducting order in two-dimensional crystals. With a free-energy that explicitly accounts for the competition between commensurate and incommensurate ... More
Discussing Quantum Aspects of Higher-Derivative 3D-Gravity in the First-Order FormalismFeb 02 2010In this paper, we reassess the issue of deriving the propagators and identifying the spectrum of excitations associated to the vielbein and spin connection of (1+2)-D gravity in the presence of dynamical torsion, while working in the first-order formulation. ... More
Segmentation of large images based on super-pixels and community detection in graphsDec 12 2016Image segmentation has many applications which range from machine learning to medical diagnosis. In this paper, we propose a framework for the segmentation of images based on super-pixels and algorithms for community identification in graphs. The super-pixel ... More
Efficient Computation of Multiple Density-Based Clustering HierarchiesSep 13 2017Jun 07 2018HDBSCAN*, a state-of-the-art density-based hierarchical clustering method, produces a hierarchical organization of clusters in a dataset w.r.t. a parameter mpts. While the performance of HDBSCAN* is robust w.r.t. mpts in the sense that a small change ... More
Riemann-Cartan Space-times of Gödel TypeNov 20 1997A class of Riemann-Cartan G\"odel-type space-times are examined in the light of the equivalence problem techniques. The conditions for local space-time homogeneity are derived, generalizing previous works on Riemannian G\"odel-type space-times. The equivalence ... More
Abelian Higgs Model Effective Potential in the Presence of VorticesJun 06 2005Nov 08 2005We determine the contribution of nontrivial vacuum (topological) excitations, more specifically vortex--strings of the Abelian Higgs model in 3+1 dimensions, to the functional partition function. By expressing the original action in terms of dual transformed ... More
Proximity force approximation and specular reflection: Application of the WKB limit of Mie scattering to the Casimir effectMar 06 2018The electromagnetic Casimir interaction between two spheres is studied within the scattering approach using the plane-wave basis. It is demonstrated that the proximity force approximation (PFA) corresponds to the specular-reflection limit of Mie scattering. ... More
The Causal Interpretation of Dust and Radiation Fluids Non-Singular Quantum CosmologiesOct 17 1997We apply the causal interpretation of quantum mechanics to homogeneous and isotropic quantum cosmology where the sources of the gravitational field are either dust or radiation perfect fluids. We find non-singular quantum trajectories which tends to the ... More
Cold black holes and conformal continuationsSep 20 2006We study Einstein gravity minimally coupled to a scalar field in a static, spherically symmetric space-time in four dimensions. Black hole solutions are shown to exist for a phantom scalar field whose kinetic energy is negative. These ``scalar black holes'' ... More
An algebraic proof on the finiteness of Yang-Mills-Chern-Simons theory in D=3Apr 27 1999A rigorous algebraic proof of the full finiteness in all orders of perturbation theory is given for the Yang-Mills-Chern-Simons theory in a general three-dimensional Riemannian manifold. We show the validity of a trace identity, playing the role of a ... More
Black Hole PerturbationDec 12 1997We present analytic calculations of gravitational waves from a particle orbiting a black hole. We first review the Teukolsky formalism for dealing with the gravitational perturbation of a black hole. Then we develop a systematic method to calculate higher ... More
Quantization of Friedmann-Robertson-Walker spacetimes in the presence of a negative cosmological constant and radiationAug 20 2005We quantize three Friedmann-Robertson-Walker models in the presence of a negative cosmological constant and radiation. The models differ from each other by the constant curvature of the spatial sections, which may be positive, negative or zero. They give ... More
Plasmonic Hot Spots in Triangular Tapered Graphene MicrocrystalsSep 07 2013Recently, plasmons in graphene have been observed experimentally using scattering scanning near-field optical microscopy. In this paper, we develop a simplified analytical approach to describe the behavior in triangular samples. Replacing Coulomb interaction ... More
Phosphorene oxides: bandgap engineering of phosphorene by oxidationOct 15 2014We show that oxidation of phosphorene can lead to the formation of a new family of planar (2D) and tubular (1D) oxides and sub-oxides, most of them insulating. This confers to black phosphorus a native oxide that can be used as barrier material and protective ... More
Reply to "Comment on 'Quantization of FRW spacetimes in the presence of a cosmological constant and radiation'"Feb 22 2007The Comment by Amore {\it et al.} [gr-qc/0611029] contains a valid criticism of the numerical precision of the results reported in a recent paper of ours [Phys. Rev. D {\bf 73}, 044022 (2006)], as well as fresh ideas on how to characterize a quantum cosmological ... More
Resonant tunneling in graphene pseudomagnetic quantum dotsJun 19 2013Realistic relaxed configurations of triaxially strained graphene quantum dots are obtained from unbiased atomistic mechanical simulations. The local electronic structure and quantum transport characteristics of y-junctions based on such dots are studied, ... More
Unified description of the dc conductivity of monolayer and bilayer graphene at finite densities based on resonant scatterersOct 19 2010Apr 06 2011We show that a coherent picture of the dc conductivity of monolayer and bilayer graphene at finite electronic densities emerges upon considering that strong short-range potentials are the main source of scattering in these two systems. The origin of the ... More
On String Tunneling in Power Law Inflationary UniversesAug 31 1993We consider the evolution of circular string loops in power law expanding universes represented by a spatially flat Friedman-Robertson-Walker metric with scale factor $a(t)\propto t^p$ where $t$ is the cosmic time and $p\geq 0$. Our main result is the ... More
Can noncommutativity affect the whole history of the Universe?Sep 16 2011Feb 11 2016We study a classical, noncommutative (NC), Friedmann-Robertson-Walker cosmological model. The spatial sections may have positive, negative or zero constant curvatures. The matter content is a generic perfect fluid. The initial noncommutativity between ... More
Localized states at zigzag edges of bilayer grapheneJul 25 2007We report the existence of zero energy surface states localized at zigzag edges of bilayer graphene. Working within the tight-binding approximation we derive the analytic solution for the wavefunctions of these peculiar surface states. It is shown that ... More
A Comment on the Topological Phase for Anti-Particles in a Lorentz-violating environmentMar 11 2006Aug 09 2006Recently, a scheme to analyse topological phases in Quantum Mechanics by means of the non-relativistic limit of fermions non-minimally coupled to a Lorentz-breaking background has been proposed. In this letter, we show that the fixed background, responsible ... More
Pseudomagnetic fields in graphene nanobubbles of constrained geometry: A molecular dynamics studyJun 04 2014Sep 16 2014Analysis of the strain-induced pseudomagnetic fields (PMFs) generated in graphene nanobulges under three different substrate scenarios shows that, in addition to the shape, the graphene-substrate interaction can crucially determine the overall distribution ... More
Lorentz-violating corrections on the hydrogen spectrum induced by a non-minimal couplingApr 20 2006The influence of a Lorentz-violating fixed background on fermions is considered by means of a torsion-free non-minimal coupling. The non-relativistic regime is assessed and the Lorentz-violating Hamiltonian is determined. The effect of this Hamiltonian ... More
Response to comment on "Broken translational and rotational symmetry via charge stripe order in underdoped YBa2Cu3O6+y"Feb 03 2016Fine questions our interpretation of unidirectional-stripes over bidirectional-checkerboard, and illustrates his criticism by simulating a momentum space structure consistent with our data and corresponding to a checkerboard-looking real space density. ... More
Current NuMI/MINOS Oscillation ResultsMay 15 2008The MINOS experiment is now making precise measurements of the nu_mu disappearance oscillations seen in atmospheric neutrinos, and will extend our reach towards the so far unseen theta_13 by looking for nu_e appearance in the nu_mu beam. It does so by ... More
Transport properties of graphene with one-dimensional charge defectsAug 03 2010Apr 14 2011We study the effect of extended charge defects in electronic transport properties of graphene. Extended defects are ubiquitous in chemically and epitaxially grown graphene samples due to internal strains associated with the lattice mismatch. We show that ... More
Predicted defect induced vortex core switching in thin magnetic nanodisksSep 24 2009We investigate the influence of artificial defects (small holes) inserted into magnetic nanodisks on the vortex core dynamics. One and two holes (antidots) are considered. In general, the core falls into the hole but, in particular, we would like to remark ... More
Ferromagnetic phases due to competing short- and long-range interactions in the spin-S Blume-Capel modelApr 19 2018We broaden the study of the statistical physics of the spin-$S$ Blume-Capel model with ferromagnetic mean-field interactions $J$ in competition with short-range antiferromagnetic interactions $K$ in a linear chain in the thermodynamic limit. This work ... More