Ferromagnetic Magnetization
Mostrando 13-24 de 45 artigos, teses e dissertações.
-
13. Simulações numéricas de Monte Carlo aplicadas no estudo das transições de fase do modelo de Ising dipolar bidimensional / Numerical Monte Carlo simulations applied to study of phase transitions in two-dimensional dipolar Ising model
Two-dimensional spin model with nearest-neighbor ferromagnetic interaction and long-range dipolar interactions exhibit a rich phase diagram, whose characteristics have been exploited by several studies in the recent literature. Furthermore, the possibility of explain observed phenomena in ultrathin magnetic films, which have many technological applications,
Publicado em: 2009
-
14. 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
-
15. The spin-1/2 ising model with skew magnetic field at high temperatures
We calculate the thermodynamics of the one-dimensional spin-1/2 Ising model in the presence of a constant skew magnetic field. We obtain the high-temperature expansion of its Helmholtz free energy (HFE), for the ferromagnetic and antiferromagnetic cases, up to order beta7. This expansion permits us to obtain the behaviour of the model for $ |J| \beta \stackr
Brazilian Journal of Physics. Publicado em: 2008-03
-
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
-
17. 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
-
18. 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
-
19. Structural and magnetic properties of the half-ferromagnetic Co2+x+yMn1-xAl1-y alloys
Co2+x+yMn1-xAl1-y intermetallic compounds have been prepared by arc melting and studied with X-ray diffraction and magnetization measurements to ascertain the effect of deviations of composition from the stoichiometry on the ferromagnetism of this system. Hysteresis loops registered at room temperature show a soft ferromagnetic behavior in excess Co. In off-
Brazilian Journal of Physics. Publicado em: 2007-12
-
20. 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
-
21. 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
-
22. 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
-
23. Studies of the magnetic properties on Mn-doped GaAs and Zn1-xCoxO thin films / Estudos das propriedades magneticas dos filmes finos de GaAs diopado com Mn e de Zn1-xCoxO
Ferromagnetic semiconductors (FM) are compounds of technological interest due to the possibility of combining their charge and spin degrees of freedom when producing electronic devices. In particular, semiconductor thin films doped with transition metal have become focus of intense scientific investigation since ferromagnetism with reasonably high Curie temp
Publicado em: 2007
-
24. 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