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Master's Dissertation
DOI
https://doi.org/10.11606/D.76.2007.tde-21082008-111614
Document
Author
Full name
Ivan Silvestre Paganini Marin
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2007
Supervisor
Committee
Sipahi, Guilherme Matos (President)
Gobato, Yara Galvão
Menezes, Jose Carlos Egues de
Title in Portuguese
Propriedades eletrônicas de heteroestruturas semicondutoras magnéticas diluídas.
Keywords in Portuguese
Heteroestruturas
Semicondutores magnéticos diluídos
Simulação computacional
Spintrônica.
Abstract in Portuguese
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 diferentes íons magnéticos. As equacoes de massa efetiva são resolvidas de forma autoconsistente com o auxílio da equacao de Poisson. As interacoes de spin-órbita e de troca-correlacao, na aproximacao de densidade local, são incluídas no cálculo. O método e aplicado para o estudo das estruturas de bandas e densidades de carga com separacao por spin do portador de heteroestruturas com dopagem tipo-n e tipo-p, variando a geometria dos pocos magnéticos e também o período da super-rede, as densidades de portadores e as concentracoes de íons magnéticos. Solucoes autoconsistentes da equacao de massa efetiva são encontradas para o oxido semicondutor (Zn,Co)O. Será mostrada a separacao de portadores por spin em funcao dos parâmetros variados, simulando diversas concentracoes possíveis, utilizadas em sistemas descritos na literatura, e será analisado o comportamento dos perfis de potencial. Usando os dados obtidos, um diagrama de fases será traçado com base na polarizacao total ou parcial dos portadores, e o seu comportamento será discutido. Também serão mostradas as estruturas de bandas, os perfis de potencial e as distribuicoes de carga do semicondutor (GaMn)As, variando as densidades de portadores e a direcao do campo magnético intrínseco, gerado pela dopagem com íons magnéticos. Os resultados obtidos neste trabalho podem servir de guia para futuras experiências e para o desenvolvimento de dispositivos com semicondutores magnéticos diluídos baseados em (Zn,Co)O e (Ga,Mn)As. Os métodos aqui descritos são gerais e podem ser utilizados para outros materiais.
Title in English
Electronic properties of diluted magnetic semiconductor heterostructures
Keywords in English
Computacional simulation
Diluted magnetic semiconductors
Heterostructures
Spintronics.
Abstract in English
This work presents a self-consistent multiband effective mass theory applied to diluted magnetic semiconductor heterostructures, generalized to include parameters of different ma- terials. The magnetic interaction is described by a mean-field approximation based on indirect- exchange mecanism, with the possibility of inclusion of different magnetic ions. The effective mass equations are solved self-consistently with the help of the Poisson equation. Spin-orbit and exchange-correlation interactions are included in the simulation in the local density appro- ximation. The method is used to study band structures and charge densities separated by spin in n- and p-type heterostructures. The magnetic well's geometry, the superlattice period, the carrier density and the magnetic ion concentration are changed. Self-consistent solutions of the effective mass equation are found for the semiconductor oxide (Zn,Co)O. Charge separation by spin will be show in function of the variation of the simulation parameters, simulating several ion concentrations and charge densities used in systems described in literature, and the potenti- als profiles will be analised. Using the data obtained a phase diagram will be plotted, based on the carrier total or partial carrier polarization, and a model for the behavior of the phase diagram will be discussed. It will also be shown band structures, potential profiles and charge densities of the (Ga,Mn)As semiconductor, varying it carrier density and the direction of the intrinsic magnetic field, generated by the magnetic ions that doped the heterostructure. The results ob- tained in this work can be used as a guide in future experiences and development of devices with diluted magnetic semiconductors based on (Zn,Co)O and (Ga,Mn)As. The methods here described are general and can be used for other materials.
 
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Publishing Date
2009-08-25
 
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