Magnetic Vortex
Mostrando 1-12 de 29 artigos, teses e dissertações.
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1. Effect of an columnar defect on vortex configuration in a superconducting mesoscopic sample
In this work we investigate the vortex dynamics in a square mesoscopic superconducting cylinder in the presence of an applied magnetic field parallel to its axis. The rectangular cross-section of the sample is L² and an engineered columnar defect of area d² at the center is taken into account; L = 12ξ(0) for all simulations while d varies discretely from
Brazilian Journal of Physics. Publicado em: 2009-12
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2. Dinâmica de spins na presença de defeitos em estruturas magnéticas confinadas: aplicações a nanodiscos magnéticos / Spin dynamics in the presence of defects on confined magnetic structures: applications the magnetic nanodisk
Neste trabalho nós investigamos a influência de defeitos artificiais inseridos em nanodiscos magnéticos na dinâmica do núcleo do vórtice. Primeiro consideramos a presença de buracos. A dinâmica foi analisada inicialmente na presença de um buraco e depois na presença de dois buracos. No geral, o núcleo cai no defeito mas, na presença de um único
Publicado em: 2009
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3. Interação da matéria de vórtices com estruturas de defeitos : detecção das primeiras penetrações
This thesis results from a systematic study of the interactions between penetrated vortices and pinning centers carried out on structured superconductors films of YBCO, Nb and Pb. A regular array of pinning centers (antidots, ADs) was inserted in those samples by mechanical indentations (in YBCO and Nb films), and by a lithographic processes (Pb). The struct
Publicado em: 2009
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4. Pinning of Abrikosov Vorticein MG B IND. 2 addition of NI nanoparticles / Aprisionamento dos Vortices de Abrikosov no MG B IND. 2 atraves da adição de nanoparticulas de NI
Since the discovery of the phenomenon of superconductivity in magnesium diboride (MgB2) in the year 2001, the vortex dynamics in this material has been widely studied, because this phenomenon can cause the destruction of the superconducting state. This study intends to assess the impact on the pinning of vortex and the behavior of the critical current densit
Publicado em: 2008
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5. Observação de vortices magneticos em calotas tridimensionais submicrometricas / Magnetic vortex observation in sub-micrometric tri-dimensional caps
Neste trabalho fizemos um estudo sistemático de filmes compostos por multicamadas Co/Pd depositados sobre arranjos auto-organizados de esferas de látex submicrométricas (50 ? 1000 nm). O filme depositado sobre a esfera (não-magnética) forma uma calota magnética com espessura variável. As espessuras de Co e Pd foram escolhidas de modo a obter duas clas
Publicado em: 2008
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6. Transição ordem-desordem da matéria de vórtices em supercondutores detectada através do terceiro harmônico da suscetibilidade AC
Although a vortex state, in type II superconductors, has been anticipated more than 50 years ago, a great deal of theoretical and experimental efforts has still been done in an attempt to investigate how the dynamics of these structures depends on external excitations and on the inherent properties of the underlying superconducting material, such as inhomoge
Publicado em: 2008
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7. Condensation of vortex-strings: effective potential contribution through dual actions
Topological 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 the vacuum and confinement through the condensation of magnetic monopoles and vortices. Other applications are related to the role of these topol
Brazilian Journal of Physics. Publicado em: 2007-03
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8. Propriedades de equilÃbrio e de transporte da matÃria de vÃrtices em nanoestruturas supercondutoras
In the present thesis, we study theoretically the equilibrium properties and dynamics of the vortex matter in two classes of nanostructured superconductors: (i) mesoscopic samples, with dimensions comparable with the penetration depth; and (ii) films with periodic array of artificial traps. In both cases, the vortex lattice symmetry is strongly dependent on
Publicado em: 2007
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9. Monte Carlo simulations of ultrathin magnetic dots
In this work we study the thermodynamic properties of ultrathin ferromagnetic dots using Monte Carlo simulations. We investigate the vortex density as a function of the temperature and the vortex structure in monolayer dots with perpendicular anisotropy and long-range dipole interaction. The interplay between these two terms in the hamiltonian leads to an in
Brazilian Journal of Physics. Publicado em: 2006-09
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10. Superconducting properties of mesoscopic squares
We apply the complete nonlinear Time Dependent Ginzburg Landau (TDGL) equations to study the vortex dynamics in a mesoscopic type II superconductor using the numerical method based on the technique of gauge invariant variables. The solution of these equations shows how the vorticity penetrates into and goes out of the superconductor through the surface bound
Brazilian Journal of Physics. Publicado em: 2006-09
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11. ConfiguraÃÃo, anisotropia e defeitos em uma rede de vÃrtices na presenÃa de nanoarmadilhas
Since Abrikosov s work in 1957, it. has been clear the vortex lattice existence and stability in specific magnetic fields and temperature values of type ll super- conductors. On external currents and Thermic fluctuations, vortices move through the superconductor salable resulting thermal dissipation. But it is salvage to most. actual technologic applications
Publicado em: 2006
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12. COMPORTAMENTO DE VÓRTICES EM NANODISCOS MAGNÉTICOS NA PRESENÇA DE DEFEITOS NÃO-MAGNÉTICOS
In recent years, the progress of the nanotechnology allowed the manufacture of magnetic samples with dimension in the nanometric scale, as well as the evolution of experimental techniques to measure its properties. It was verified experimentally that vortices appear as states of magnetization of minimum energy in magnetic dots. In nanometric scale, the effec
Publicado em: 2006