Phase Ferromagnetic
Mostrando 13-24 de 48 artigos, teses e dissertações.
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13. Ferromagnetic resonance study of the anisotropies uniaxial and unidirectional magnetic bilayer and tricamadas / Estudo por ressonância ferromagnética das anisotropias uniaxial e unidirecional em bicamadas e tricamadas magnéticas
The Ferromagnetic Resonance (FMR) technique at the X-band (~ 9.70 GHz) and Q-band (~ 34.0 GHz) was used to study the magnetic properties of NiO/Co, NiO/Py and Py/FeMn bilayers, and Co/NiO/Co trilayers with different thicknesses, deposited by dc magnetron sputtering technique in the presence of a 400 Oe magnetic field. The FMR experiments were all done at roo
Publicado em: 2009
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14. Electron magnetic resonance in studies of biologically-relevant systems. / Ressonância magnética eletrônica no estudo de sistemas de interesse biológico
In this work, we made use of the Electron Paramagnetic Resonance (EPR) spectroscopy along with the so-called reporter group technique and extensive spectral simulations by means of the software NLSL to investigate the interaction of nicotine with model membranes. Besides that we also employed Ferromagnetic Resonance (FMR), which is a technique similar in man
Publicado em: 2009
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15. Propriedades magnÃticas do nanocompÃsito (Fe1-xCox)y(MnO)1-y
In the present work were investigated the magnetic properties of ferromagnetic nanocomposites (Fe1−xCox)y(MnO)1−y, x = 0.4 and 0.6 e y = 0.35, 0.65 and 1, produced by mechanical-alloying. Structural and morphological characterization were made by x-ray diffraction using Scherrer equation, Williamson-Hall plot and Rietveld refinement. The refineme
Publicado em: 2009
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16. Síntese, sinterização e caracterização de ferritas à base de Ni-Zn
Were synthesized different ferrites NixZn1-xFe2O4 (0,4 ≤ x ≤ 0,6) compositions by using citrate precursor method. Initially, the precursors citrates of iron, nickel and zinc were mixed and homogenized. The stoichiometric compositions were calcined at 350C without atmosphere control and the calcined powders were pressed in pellets and toroids. The
Publicado em: 2008
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17. Estado fundamental do modelo de Hubbard estendido na cadeia AB2
In this dissertation we study the extended Hubbard model in the AB2 chain. The model hamiltonian contains a kinetic term, parameterized by t, and two terms of coulomb repulsion,U (intra-site) and V (inter-site). Considering a peculiar local exchange symmetry of the chain, as well as global symmetries of the Hubbard hamiltonian, we have applied the numerical
Publicado em: 2008
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18. 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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19. Propriedades magneticas de filmes de ligas GD-Cr / Magnetic properties of Gd-Cr alloy films
Vapor condensation techniques are very useful for preparation of alloys whose components have no mutual solubility under equilibrium conditions In this work, one of these techniques ? sputtering ? has been used to fabricate metastable GdXCr1-X alloys whose magnetic properties were investigated as a function of the Gd concentration, x. Grazing incidence angle
Publicado em: 2008
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20. Síntese análise das propriedades magnéticas da ferrita de NiMg e características de absorção de radiação
Foram sintetizadas diferentes composições da ferrita Ni1-xMgxFe2O4 com (0,2 ≤ x ≤ 0,7) pelo uso do método dos citratos precursores. Para se obter a fase estequiométrica Ni1-xMgxFe2O4, inicialmente foram misturados e homogeneizados os citratos precursores de ferro, níquel e magnésio. As composições estequiométricas foram calcinadas entre
Publicado em: 2008
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21. Characterization of the structural and magnetic properties of Nd16Co76-xRu xC7B alloys
The Nd16Co76-xRu xC7B system has been investigated to assess the effect of boron-carbon combined addition on the ferromagnetic behavior of these intermetallic compounds. The results indicate that the addition of 1 at.% B favors the formation of the tetragonal magnetic phase 2:14:1 in these alloys. With the increase of the Ru concentration is observed an expa
Brazilian Journal of Physics. Publicado em: 2007-09
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22. The van Hemmen model in the presence of a random field
The van Hemmen model with a random field is studied to analyze the tricritical behavior in the Ising spin glass phase. The free energy and phase diagram (T versus H and T versus Jo/J, where H is the root mean square deviation of the magnetic field, Jo and J are the ferromagnetic and root mean square deviation exchange, respectively) are calculated for the mo
Brazilian Journal of Physics. Publicado em: 2007-06
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23. Parameter symmetry in ferromagnetic superconductors / Simetria do parametro de ordem em supercondutores ferromagneticos
In this dissertation, we present a study of the order-parameter symmetry in ferromagnetic superconductors. Our approach is inspired on the Landau Theory of Phase Trasition or, more precisely, on the idea that a second order phase transition is a symmetry breaking process where the ordered phase of the system is described by a subgroup of the highly symmetric
Publicado em: 2007
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24. Estado fundamental e excitações coletivas de condensados de Bose-Einstein espinoriais / Ground state and collective excitations od spinor Bose-Einstein condensates
In the framework of the Bogoliubov theory, we determined the equilibrium configurations and the collective excitations of a homogeneous Bose-Einstein S = 1 spinor condensate, in the presence and absence of an externa1 magnetic field. In this thesis we found the equilibrium configurations as function of the parameters and m, where q is the intensity of the qu
Publicado em: 2007