Magnetic Anisotropy
Mostrando 25-36 de 97 artigos, teses e dissertações.
-
25. Estudo in-situ de filmes magnéticos ultrafinos por magnetometria Kerr e técnicas de superfície
The aim of this work is to apply Kerr magnetometry to ultra-thin magnetic films. A Kerr magnetometer operating in ultra high vacuum is described, as well as the modications and optimizations we have done, to achieve atomic monolayer sensibility. We present measurements performed on samples with different magnetic properties, such as exchange bias effect, sys
Publicado em: 2009
-
26. CaracterÃsticas microestruturas e propriedades magnÃticas de arranjos de nanofios magnÃticos
Este trabalho tem o objetivo de relacionar as caracterÃsticas microestruturais com as propriedades magnÃticas em arranjos de nanofios ordenados depositados em membranas porosas de Ãxido de alumÃnio. Inicialmente à apresentado um estudo sobre a preparaÃÃo das membranas e a posterior eletrodeposiÃÃo dos fios no interior dos poros. A seguir sÃo descri
Publicado em: 2009
-
27. Multicamadas magnéticas de telureto de európio e semicondutores iv-vi crescidas por epitaxia de feixe molecular / Magnetic multilayers of europium telluride and IV-VI semiconductors grown by molecular beam epitaxy
In this work, thin EuTe films and EuTe/PbTe(SnTe) superlattices were grown, and their structural and magnetic properties were characterized. The molecular beam epitaxial growth parameters of the samples were optimized, particularly those of the EuTe/SnTe SLs. To this goal, the growth modes of EuTe on SnTe and vice versa were investigated, and the influence o
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 07/10/2008
-
28. Efeitos de tamanho finito e interface em nanopartículas e nanocolóides magnéticos
In this work, we investigated magnetic nanoparticles based on copper ferrite, with mean sizes ranging between 3,5 nm e 10,7 nm. Such nanomaterials are chemically synthesized by hydrothermal coprecipitation and allow elaborating magnetic nanocolloids in aqueous and acidic medium thanks to a core-shell strategy that prevent the nanoparticles from dissolution.
Publicado em: 2008
-
29. Síntese e caracterização de nanopartículas de ferritas / Sysnthesis and characterization of fenites nanoparticles
Magnetic nanoparticles have been extensively investigated, motivated by their potential technological and biomedical applications as well as in search of a better understanding of the physical properties modifications induced by nanoscale size. Synthesizing nanoparticles with a narrow size dispersion and good morphological, structural and stoichiometric homo
Publicado em: 2008
-
30. Magnetic and barocaloric effect in physical systems with two energy levels / Efeitos magnetocalórico e barocalórico em sistemas físicos com dois níveis de energia
In this work we study the theoretical aspects of the magnetocaloric and barocaloric effect in simple physical systems with two and four energy levels. In order to do that, we used a Hamiltonian that consider local magnetic moments interacting among them and with an external magnetic field.We include in the Hamiltonian the magnetoelastic interaction, and an e
Publicado em: 2008
-
31. New functionals for the anisotropic Heisenberg model / Novos funcionais para o modelo de Heisenberg anisotrópico
The Heisenberg Model is generally recognized in the study of electromagnetism with origin in localized magnetic moments. Similar to the well known classical Ising model, it incorporates, however, quantum flutuations. We are interested in antiferromagnetic systems described by the Heisenberg Hamiltonian with exchange anisotropy and, eventually, non-null magne
Publicado em: 2008
-
32. Evolução estrutural brasiliana da Província Borborema na região de Campina Grande, (PB) / Brasilian structural evolution of Borborema Province in the Campina Grande region (PB)
The systematic mapping of Campina Grande sheet (1:100.000) is very important to understand the structural and geochronological relations between different terranes of the Transversal Zone, Borborema Province (NE Brazil). The mapped area is an excellent natural laboratory to apply classical and modern techniques of structural geology for the study of mechanis
Publicado em: 2008
-
33. Propriedades físicas de bicamadas magnéticas
The magnetic order of bylayers composed by a ferromagnetic film (F) coupled with an antiferromagnetic film (AF) is studied. Piles of coupled monolayers describe the films and the interfilm coupling is described by an exchange interaction between the magnetic moments at the interface. The F has a cubic anisotropy while the AF has a uniaxial anisotropy. We ana
Publicado em: 2007
-
34. 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
-
35. Estudo das propriedades estruturais locais de fluidos magnéticos : da nanopartícula à dispersão
Local structural properties of magnetic fluids based on nanosized particles of zinc, copper or nickel ferrite are investigated. Nanograins prepared by a soft chemistry method are dispersed in acidic medium thanks to a core-shell strategy that prevents the particles from dissolution. Their chemical composition is no longer homogeneous and they can be describe
Publicado em: 2007
-
36. "Caracterização estrutural e óptica de elastômeros dopados com ferrofluidos" / Optical and Structural Characterization of Elastomers Dopeds with Ferrofluids
This work aims the structural, mechanical and optical characterization of urethane/urea elastomers (PU/PBDO), based on polypropylene oxide and polybutadiene diol, pure, after swelling in toluene and doped with ferrofluid. The ratios in weight % of PU and PBDO used are 40/60, 50/50, 60/40 and 80/20. The structural analysis were made through of polarized light
Publicado em: 2007