Loreto, R. P.; Gonçalves, R. S.; Pereira, A. R.; Araujo, C. I. L. de; Nascimento, F. S.; Borme, J.; Cezar, J. C.; Nisoli, C.(Journal of Physics: Condensed Matter, 2019)
In this work, we explore a kind of geometrical effect in the thermodynamics of artificial spin ices (ASI). In general, such artificial materials are athermal. Here, We demonstrate that geometrically driven dynamics in ASI ...
Fernandes, R. L.; Lopes., R. J. C; Pereira, A. R(Solid State Communications, 2019-03)
We have investigated (numerically) skyrmions constituted by two merons in two-dimensional Heisenberg antiferromagnets. The behavior and stability of these topological pseudo-particles are analyzed in discrete and finite ...
Rodrigues, Nathann T; Oliveira, Tiago J(Journal of Physics A: Mathematical and Theoretical, 2014)
We study a generalized interacting self-avoiding walk (ISAW) model with nearest- and next nearest-neighbor (NN and NNN) interactions on square and cubic lattices. In both dimensions, the phase diagrams show coil and globule ...
Moura, A. R.; Lopes, R. J. C.(Journal of Magnetism and Magnetic Materials, 2019-02-15)
We used the Self-Consistent Harmonic Approximation (SCHA) to study the thermodynamics of the precession magnetization in a two-dimensional isotropic ferromagnet. The SCHA treats the Hamiltonian in terms of the canonically ...
Fonseca, Jakson M.; Moura-Melo, Winder A.; Pereira, Afranio R.; Carvalho-Santos, Vagson L.(The European Physical Journal B, 2016-06)
An effective Hamiltonian describing the surface states of a toroidal topological insulator is obtained, and it is shown to support both bound-states and charged zero-modes. Actually, the spin connection induced by the ...
Gomes, Joaquim P.; Felix, Jorlandio F.; Mondal, Sanjib; Ghosh, Anupam; Gobato, Y. Galvão; Galeti, H. V. Avanço; Choudhuri, B.; Dwivedi, S. M. M. Dhar; Henini, M.; Mondal, Aniruddha; Piton, M. Rizzo(Journal of Materials Science: Materials in Electronics, 2018-11)
We have investigated the electrical and optical properties of erbium (Er3+) doped TiO2 thin films (Er:TiO2 TFs) grown by sol–gel technique on glass and silicon substrates. The samples were characterized by field emission ...
We revisit the classical theory of a relativistic massless charged point particle with spin and interacting with an external electromagnetic field. In particular, we give a proper definition of its kinetic energy and its ...
Dias, Rafael F.; Costa, Cleidineia C. da; Manhabosco, Taise M.; Oliveira, Alan B. de; Matos, Matheus J. S.; Soares, Jaqueline S.; Batista, Ronaldo J. C.(Chemical Physics Letters, 2019-01-16)
We employed PBE and BLYP semi-local functionals and the van der Waals density functional of Dion et al. (2004) (vdW-DF) to investigate structural properties of liquid acetonitrile and methanol. Among those functionals the ...
Rojas, Onofre; Souza, Sérgio M. de; Moura-Melo, Winder A.(Physica A: statistical mechanics and its applications, 2007-01-01)
Thermodynamical properties of spin-S Ising chains can nowadays be easily obtained using numerical calculation. However, from a mathematical point of view, its exact solution for arbitrary spin is still a challenge. Only ...
Pereira, A. R.; Pires, A. S. T.; Moura, A. R.(Journal of Magnetism and Magnetic Materials, 2014-05)
In this paper we study the influence of the single-ion anisotropy in the two-dimensional biquadratic Heisenberg model (ABHM) on the square lattice at zero and finite low temperatures. It is common to represent the bilinear ...
In this paper we consider a model for gravity in four-dimensional space-time originally proposed by Chamseddine, which may be derived by dimensional reduction and truncation from a five-dimensional Chern–Simons theory. Its ...
Five-dimensional Chern–Simons theory with (anti-)de Sitter SO(1,5) or SO(2,4) gauge invariance presents an alternative to general relativity with cosmological constant. We consider the zero modes of its Kaluza–Klein ...
Martins, Marcelo Lobato; Sales, J. A. de; Moreira, J. G.(Journal of Physics A: Mathematical and General, 1999-02-12)
We propose a method to detect phase transitions in discrete lattice models based on the roughness exponent. This approach is applied to the one-dimensional Domany-Kinzel cellular automaton (CA). Our results, obtained by ...
Bacterial attachment to stainless steels AISI (American Iron and Steel Institute) 304 and 316, the preferred material choices for food equipment, is a very important food safety consideration. The purpose of the present ...
Felix, J. F.; Cunha, D. L. da; Pereira, G. F. C.; Aguiar, J. Albino; Azevedo, W. M. de(Materials Research Bulletin, 2014-01)
This article presents a chemical bottom-up synthesis of highly crystalline and nanostructured hydrocerussite (Pb3(CO3)2(OH)2) with hexagonal morphology prepared by laser ablation in liquid. The results demonstrate that is ...
Mansur Filho, J. C.; Silva, A. G.; Carvalho, A. T. G.; Martins, M. L.(Physica A: Statistical Mechanics and its Applications, 2005-05-25)
We report some experimental results for quasi-two-dimensional electrocrystallization of copper under magnetic fields. Such results are theoretically investigated by large scale simulations of a DLA-like model in which ...
Freitas, Walter A.; Moura-Melo, Winder A.; Pereira, A. R.(Physics Letters A, 2005-03-14)
This work is devoted to the study of how spin texture excitations are affected by the presence of a static non-magnetic impurity whenever they lie on a conical support. We realize a number of novelties as compared to the ...
Brandao, Mariana P.; Gouvea Neto, Marina; Anjos, Virgílio de Carvalho dos; Bell, Maria José V.(Food Control, 2017-06-07)
The increasing importance of goat milk renews the need to examine the authenticity of goat milk powder and to identify frauds with cow milk powder. The use of front-face and time-resolved fluorescence techniques to identify ...
Moura-Melo, W. A.; Pereira, A. R.; Mól, L. A. S.; Pires, A. S. T.(Physics Letters A, 2007-01-01)
We study magnetic vortex-like excitations lying on a conic space background. Two types of them are obtained. Their energies appear to be linearly dependent on the conical aperture parameter, besides of being logarithmically ...
Belo, L. R. A.; Oliveira Neto, N. M.; Moura Melo, W. A.; Pereira, A. R.; Ercolessi, Elisa(Physics Letters A, 2007-06-11)
Heisenberg-like spins lying on the pseudosphere (a 2-dimensional infinite space with constant negative curvature) cannot give rise to stable soliton solutions. Only fractional solutions can be stabilized on this surface ...