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Magnetismo de nanofios de cobalto e níquel fabricados por eletrodeposição em alumina anódica porosa
(Universidade Federal de São Carlos, 2015-03-04)
In this thesis were investigated the magnetic properties of magnetic nanowire arrays of Co and Ni electrodeposited in porous anodic alumina templates. The electrochemical method was employed in the manufacturing steps of ...
Modelos dinâmicos de magnetização aplicados em compósitos magnetoelétricos
(Universidade Federal de São Carlos, 2014-04-01)
In this thesis we study the magnetic properties of the multiferroic composite (1-x)Pb(Mg1/3Nb2/3)-xPbTiO3/CoFe2O4 (PMN-PT/CFO) sintered by hot forging. Magnetization as a function of magnetic field, magnetoelectric effect ...
Comportamento multicrítico no modelo de Heisenberg frustrado: transições de fases clássica e quântica
(Universidade Federal de São Carlos, 2011-09-01)
In this work we study the critical behavior of systems described by the Anysotropic- Heisenberg model of spin 1/2 with competitive interactions (J1-J2 Model) on planes, and interplane nearest-neighbor interactions. We ...
Modelos de spins geometricamente frustrados: transição de fase e estruturas de platores
(Universidade Federal de São Carlos, 2013-04-08)
This thesis presents a study of the magnetization plateau and the phenomenon of geometrical frustration in spin systems applied to lattices with triangular structure, as well as the results achieved by applying the ...
Ansatz de Bethe algébrico com fronteiras triangulares
(Universidade Federal de São Carlos, 2014-05-26)
In this work we study vertex models with non-diagonal boundaries, characterized by reection matrices with an upper triangular form. By means of an extension of the algebraic Bethe ansatz, we construct generalized Bethe ...
Flux avalanches in patterned superconducting thin films: ac susceptibility, morphology and related studies
(Universidade Federal de São Carlos, 2013-04-12)
Avalanches are sudden dramatic phenomena that occur in nature. The technique of magneto-optical imaging (MOI) has allowed us to observe abrupt flux entrances in superconductors, the so-called ux avalanches, due to ...
Estabilidade em equações de reação e difusão : interação entre difusibilidade e geometria em superfícies de revolução e um problema singularmente perturbado no caso de intersecção das raizes da equação degenerada
(Universidade Federal de São Carlos, 2013-03-07)
In this work we study two distinct problems. The first is a parabolic problem with variable diffusivity on surfaces of revolution. The objective is to find mechanisms of interaction between the diffusivity function and the ...
Duas involuções comutantes fixando certas variedades de Dold e certas uniões de espaços projetivos relativos a anéis diferentes
(Universidade Federal de São Carlos, 2015-04-01)
Let (M; _) be a smooth action of Z2 2 on a closed, smooth and m-dimensional manifold, with fixed point set F = m[ j=0 Fj , where Fj means the union of the components of F of dimension j. Given such a F, we can ask for the ...
Torres de sela Scherk com gênero par arbitrário em R^3
(Universidade Federal de São Carlos, 2014-02-25)
Starting from works by Scherk (1835) and by Enneper-Weierstraß (1863), new minimal surfaces with Scherk ends were found only in 1988 by Karcher (see [16, 17]). In the singly periodic case, Karcher s examples of positive ...
Operadores efetivos para guia de ondas com condição de Robin no plano e espaço
(Universidade Federal de São Carlos, 2014-05-23)
First we briefly discuss the spectral properties of the Robin Laplacian in a straight and infinitely long planar strip with Robin coupling parameter changing signs. Assuming that such parameter is a constant outside a ...