Magnetic Semiconductors
Mostrando 13-24 de 34 artigos, teses e dissertações.
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13. 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
Neste trabalho foram crescidos e investigados, dos pontos de vista estrutural e magnético, filmes finos de EuTe e superredes (SL) de EuTe/PbTe e de EuTe/SnTe. A primeira etapa do trabalho consistiu na otimização dos parâmetros de crescimento por epitaxia de feixe molecular das amostras, em particular das SLs de EuTe/SnTe. Para isto, foram investigados os
Publicado em: 2008
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14. 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
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15. 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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16. Propriedades eletrônicas de heteroestruturas semicondutoras magnéticas diluídas. / Electronic properties of diluted magnetic semiconductor heterostructures
Neste trabalho e apresentado um estudo, via teoria de massa efetiva multibanda autoconsistente de heteroestruturas de semicondutores magnéticos diluídos, generalizada para incluir parâmetros de diferentes materiais. A interacao magnética e descrita por um modelo de campo médio baseado no mecanismo de troca indireta, com a possibilidade de inclusão de d
Publicado em: 2007
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17. Desenvolvimento de processos de deposição de filmes filmes sobre substratos polimericos fotopolimerizdos / Development of process of deposition of thin films on photopolymerization polymeric substrats
A new era has begun all around the world. The quality of life and health depends more and more on the human capacity of resolving problems that are becoming longer and more complex day by day. As communication and globalization advance, time becomes scarcer and more precious. The semiconductor materials which are used to activate the logical functions, the h
Publicado em: 2007
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18. Éxcitons em semicondutores magnéticos diluídos / Excitons in diluted magnetic semiconductors
Investigamos o tunelamento ressonante de elétrons e buracos em um pouco quântico duplo assimétrico de CdTe/CdMnTe na presença de campos elétricos e magnéticos aplicados ao longo da direção de crescimento. Mostramos que neste caso é possível alcançar uma condição de tunelamento ressonante simultâneo de elétrons e buracos com spin definido, isto
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 02/08/2006
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19. Effects of disorder on the exchange coupling in (Ga,Mn)As diluted magnetic semiconductors
A theoretical study of the effects of disorder on the Mn-Mn exchange interactions for Ga1-xMn xAs diluted magnetic semiconductors is presented. The disorder is intrinsically considered in the calculations, which are performed using an ab initio total energy density-functional approach, for a 128 atoms supercell, and by considering a variety of configurations
Brazilian Journal of Physics. Publicado em: 2006-09
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20. Study of effects of interfaces in the propagation of the energy by optical modes in coaxial cylinders
We study the influence of the interfaces on the dispersion relation, energy and power flow of polaritons propagating in coaxial cylinders. We consider an infinite coaxial cylinder of internal and external radii designated by a and b, respectively, submitted to a magnetic dc field applied parallel to the z-axes. The presence of a magnetic field causes signifi
Brazilian Journal of Physics. Publicado em: 2006-09
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21. Theory of hydrogen complexes in Mn xGa1-xAs dilute magnetic semiconductors
Atomic hydrogen diffuses in semiconductor lattices and binds to impurities by forming complexes that can lead to a full neutralization of the impurity effects. In the present paper, the structural, vibrational, electronic and magnetic properties of complexes formed by H in the Mn xGa1-xAs (x=0.03) dilute magnetic semiconductor have been investigated by using
Brazilian Journal of Physics. Publicado em: 2006-06
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22. Spin relaxation and g-factor manipulation in quantum dots
Phonon-induced spin relaxation rates and electron g-factor tuning of quantum dots are studied as function of in-plane and perpendicular magnetic fields for different dot sizes. We consider Rashba and Dresselhaus spin-orbit mixing in wide and narrow-gap semiconductors, and show how Zeeman sublevels can relax via piezoelectric (GaAs) and deformation (InSb) pot
Brazilian Journal of Physics. Publicado em: 2006-06
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23. A selfconsistent calculation of the transport properties of a double barrier spin filter
A double barrier resonant tunneling device in which the well is made of a semi-magnetic material can work as an efficient spin filter. Today it is possible to make semiconductors that are ferromagnetic at room temperature. Therefore the device studied here has a great potential to be used as a polarizer, an analyzer and other spintronic applications. We disc
Brazilian Journal of Physics. Publicado em: 2006-06
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24. METODOLOGIA DE PROJETO DE CONVERSORES BOOST PARA CORREÇÃO DE FATOR DE POTÊNCIA APLIOCADA A SISTEMAS ININTERRUPTOS DE ENERGIA / A design Methodology for Boost Converters to Power Factor Correction Applied in Uninterrruptible Power Supplies
This Master Thesis presents a design methodology to a boost PFC converter operating as an Uninterruptible Power Supply rectifier input stage. This methodology defines, making use of a group of current ripples and switching frequencies, the converter minimum volume point analyzing the volumes of the boost inductor, the electromagnetic interference filter and
Publicado em: 2006