Ferromagnetic Materials
Mostrando 13-24 de 34 artigos, teses e dissertações.
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13. Ruido Barkhausen y emisión magneto acústica para la caracterización de materiales ferromagnéticos
The techniques of Barkhausen Noise (BN) and Magneto Acoustic Emission (MAE) were applied to a ferromagnetic material with the objective of correlating the obtained signals with the micro structural changes. The first step was the development of an Integral Measurement System (IMS) for the BN and MAE signals. Different devices as magnetic yoke, current source
Matéria (Rio de Janeiro). Publicado em: 2008-03
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14. O efeito magnetocalórico nas ligas Heusler Ni54[Mn(1-x)Fex]19Ga27
In this work, magnetic entropy change of nonstoichiometric Ni54[Mn(1-x)Fex]19Ga27 Heusler alloys was experimentally verified by partial substitution (up to 50%) of the Mn atoms by magnetic Fe atoms. Such study was mainly concentrated in the magneto-structural transformation region, at low temperatures. The analysis of X-ray diffraction patterns indicate that
Publicado em: 2008
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15. CORROSION OF ADVANCED STAINLESS STEEL IN PHYSIOLOGICAL SOLUTIONS / Corrosão de aços inoxidáveis avançados em meios fisiológicos
The main objective of this study was to determine the corrosion behavior of advanced stainless steels (SS) in physiological solutions to evaluate their potential for use as biomaterials. Four stainless steels were tested: a superferritic stainless steel (DIN W. Nr. 1.4575), Incoloy MA 956, containing aluminum and yttrium oxide, an austenitic stainless steel
Publicado em: 2008
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16. Crescimento e estrutura de monocamadas de Co sobre Cu90Au10(100)
O estudo das correlações entre as propriedades estruturais e magnéticas de filmes finos e ultrafinos é hoje assunto de grande interesse tanto científico como tecnológico, sendo que, dada a disponibilidade de materiais e a importância das aplicações atuais e potenciais, filmes magnéticos compostos por metais e ligas de metais de transição 3d estã
Publicado em: 2008
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17. CRESCIMENTO, ESTRUTURA E POLARIZAÇÃO DE TROCA EM BICAMADAS FERROMAGNETO / ANTIFERROMAGNETO PREPARADAS POR DEPOSIÇÃO EM CONDIÇÕES DE EPITAXIA POR FEIXE MOLECULAR: Fe / EuTe(111), Fe / Ni50Mn50(001) e Ni1-xFex / Fe50Mn50
Magnetic interaction at interfaces between different layered magnetic materials is an important current topic in physics and materials science, particularly when combining ferromagnetic metals and semiconductors. The exchange bias effect associated with the exchange coupling between antiferromagnetic (AFM) and ferromagnetic (FM) systems, has been extensively
Publicado em: 2007
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18. APLICAÇÃO DE MATERIAIS COM MAGNETOSTRICÇÃO GIGANTE EM SENSORES DE DESLOCAMENTO SEM CONTACTO / GIANT MAGNETOSTRICTIVE MATERIALS APPLIED TO CONTACTLESS DISPLACEMENT SENSORS
Magnetostriction is a property of ferromagnetic materials to deform in the presence of a magnetic field. Magnetostriction is an inherent property of magnetic materials, which is unchangeable with time. Materials exhibiting strains in the order of 10-3 are known as giant magnetostrictive materials (GMM).In this dissertation we study the application of these m
Publicado em: 2007
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19. Microscopic theory of spin waves in magnetic nanowires / Teoria microscÃpica de ondas de spin em nanofios magnÃticos
The dynamical behavior of spins in magnetic materials is affected by its geometry and dimensionality. One can find several new results in the literature exploiting the magnetic properties of low dimension systems with different geometries, since the development of new devices such as: nanosensors, high density magnetic storage, etc., is closely related to ne
Publicado em: 2007
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20. Crescimento de filmes nanométricos monocristalinos de Fe/MgO(100) por "SPUTTERING" DC
The research behind this master dissertation started with the installation of a DC sputtering system, from its first stage, the adaptation of a refrigerating system, passing by the introduction of a heating system for the chamber using a thermal belt, until the deposition of a series of Fe/MgO(100) single crystal nanometric film samples. The depo
Publicado em: 2007
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21. "Spin and magnetic properties of the III-V group semiconductors" / "Propriedades magnéticas e de spin em semicondutores do grupo III-V"
We present the results of our investigations concerning MBE grown AlGaAs/GaAs parabolic quantum well (PQW) samples. We focused on the variation of the Landé g factor along the structure of the PQWs, which occur as a consquence of its dependence on the Al content on the alloy AlGaAs. The implications are studied by Hall and Shubnikov-de Haas measurements. Sh
Publicado em: 2006
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22. The study of the magnetocaloric effect in compounds of MnAs1-xAx, A = P, Sb, Te e Mn1-xFexAs / Estudo do efeito magnetocalorico em compostos de MnAs1-xAx, A = P, Sb, Te e Mn1-xFexAs
In this work we describe the obtaining processes of the MnAs1-x Ax (A= Te, P, Sb) and Mn1-xFexAs series for several concentrations. We divided this work in two stages: in the first one the samples were obtained using a high pressure furnace and in the second one using a resistive furnaces with the samples sealed in quartz tubes. The first stage, can be split
Publicado em: 2006
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23. Linear and non-linear giant magnetoimpedance in amorphous alloys / Magnetoimpedancia gigante linear e não-linear em ligas amorfas
Não informado
Publicado em: 2005
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24. Estudo de sistemas magneticos em estruturas periodicas / Study of magnetic systems in periodic structures
In this thesis we employ the holographic lithography (HL) technique to reproduce periodic patterns that were subsequently used as masks for the deposition of magnetic materials by sputtering. The structures present the same periodicity of the previously recorded mask. One advantage of this technique is the very good aspect ratio, even for areas of the order
Publicado em: 2005