Heidelberg, Universiẗat, Diss., 2002.

Köln, University, Diss., 2004.

No description available.

Liu, Yang = 軌道簡并性對強關聯系統的磁性的研究 / 劉陽. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (p. 49-51). / Abstracts in English and Chinese. / Liu, Yang = Gui dao jian bing xing dui qiang guan lian xi tong de ci xing de yan jiu / Liu Yang. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Phenomena of Magnetism --- p.1 / Chapter 1.1.1 --- Magnetic susceptibility and classification of magnetic phases --- p.2 / Chapter 1.1.2 --- Paramagnetism and Diamagnetism --- p.3 / Chapter 1.1.3 --- "Ferromagnetism, antiferromagnetism, and ferrimagnetism" --- p.3 / Chapter 1.2 --- Models describing the magnetic system --- p.5 / Chapter 1.2.1 --- The quantum mechanical origin of the interaction between magnetic moments --- p.5 / Chapter 1.2.2 --- Heisenberg model --- p.6 / Chapter 1.2.3 --- Hubbard model --- p.7 / Chapter 1.2.4 --- Background of ferromagnetism in Hubbard model --- p.8 / Chapter 1.3 --- Two-orbital Hubbard model --- p.9 / Chapter 2 --- Low energy effective theory and perturbation method --- p.14 / Chapter 2.1 --- Perturbation by diagrams --- p.14 / Chapter 2.2 --- Illustration of the basic idea: from Hubbard model to Heisenberg model --- p.15 / Chapter 2.2.1 --- Low energy space and intermediate basis --- p.16 / Chapter 2.2.2 --- Diagrams presenting the effective coupling --- p.17 / Chapter 2.2.3 --- Operator form --- p.18 / Chapter 2.3 --- Effective Hamiltonian of quarter filled two-orbital Hubbard model in the large-U limit --- p.19 / Chapter 2.3.1 --- Low energy space and intermediate basis --- p.19 / Chapter 2.3.2 --- Diagrams presenting the effective coupling --- p.20 / Chapter 2.3.3 --- Operator form --- p.23 / Chapter 2.4 --- Two-site problem of two-orbital Hubbard model --- p.25 / Chapter 2.4.1 --- Exact solution --- p.25 / Chapter 3 --- ED method and Numerical results --- p.29 / Chapter 3.1 --- ED method --- p.29 / Chapter 3.1.1 --- Construction of Hilbert space of the many-body model --- p.30 / Chapter 3.1.2 --- Lanczos iterative algorithm --- p.30 / Chapter 3.2 --- Spin structure factor --- p.31 / Chapter 3.2.1 --- Spin structure factor changes with various filling --- p.32 / Chapter 3.2.2 --- Spin structure factor changes with various J --- p.34 / Chapter 3.2.3 --- Spin structure factor changes with various U' --- p.34 / Chapter 3.3 --- Ground state spin magnetization --- p.36 / Chapter 4 --- Quantum phase transition in 1D Half-filled Asymmetric Hubbard model --- p.38 / Chapter 4.1 --- Introduction --- p.38 / Chapter 4.2 --- Spin stiffness --- p.41 / Chapter 4.3 --- Numerical result --- p.43 / Chapter 4.4 --- Summary --- p.46 / Chapter 5 --- Summary --- p.48 / Bibliography --- p.49 / Chapter A --- Conditions of spin and orbital rotational invariant --- p.52 / Chapter A.l --- condition of spin rotational invariant --- p.52 / Chapter A.2 --- conditions of orbital rotational invariant --- p.54 / Chapter B --- Detailed calculation of effective Hamiltonian of two-orbital Hubbard model --- p.57 / Chapter C --- Perturbation of the quartic equation --- p.89

Scientologin är en nyreligiös rörelse som skildrats flitigt inom populärlitteraturen, vilket gör att den blivit något bekant för många. Syftet med denna uppsats är att använda en bekant nyreligiös rörelse och utifrån denna skapa ett undervisningsunderlag som rör innehållet i Religion 2. Uppsatsen behandlar scientologins kännetecken samt förhållande till världsreligionerna. Den teoretiska ram som arbetet innehåller är kärnan ur Russel T. McCutcheons föreskrivna sätt att studera religion utifrån rörelsens historia, rörelsen tro och världsbild, rörelsens sociala och praktiska uttryck samt rörelsens relation till övriga religioner. Denna forskning rör innehåller i Religion 2 på ett mer avgränsat och specifikt sätt än tidigare forskning kring rörelsen. Uppsatsen är en kvalitativ systematisk litteraturstudie och resultatet en sammanställning av tidigare forskning kring scientologirörelsen, utifrån frågeställningarna ovan. De slutsatser som detta arbete ger vid handen är framförallt scientologins koppling till äldre traditionella religioner som buddhism och kristendom, men också moderna andliga strömningar som new age. Vad gäller scientologins kännetecken utkristalliseras en rörelse med gnostiska drag där kunskap och självutveckling är centralt.

Würzburg, University, Diss., 2008.

Thèses (M.Sc.)--Université de Sherbrooke (Canada), 2001. / Titre de l'écran-titre (visionné le 20 juin 2006). Publié aussi en version papier.

Techn. Universiẗat, Diss., 2004--Braunschweig.

Neste trabalho estudamos algumas propriedades supercondutoras de compostos hidratados de cobalto do tipo NaxCoO2 · yH2O. Estes compostos são formados por planos de CoO2, intercalados por planos de íons de Na e moléculas de H2O, formando uma rede triangular bidimensional pelos átomos de Co. Utilizando como modelo um hamiltoniano de Hubbard estendido, foram construídas as funções de Green normal e anômala no limite U → ¥ e na aproximação de campo médio. Nos restringimos ao caso paramagnético, e estudamos a supercondutividade do sistema considerando a possibilidade de diferentes simetrias para o parâmetro de ordem da fase supercondutora. Os resultados indicam a ocorrência de supercondutividade para determinadas regiões do número de partículas, em concordância qualitativa com os dados experimentais. / In this work we study some properties of hydrated cobalt oxide, NaxCoO2 · yH2O in the superconducting phase. This compound consists of CoO2 layers interlayered by Na ions and H2O molecules, resulting in a Co triangular lattice. Our theoretical model is the extended Hubbard Model and we obtain the normal and anomalous Green’s functions in the infinite U limit by using the mean field approximation. We consider the paramagnetic case and we analyse coupling between electrons with different symmetries, so obtaining the singlet and triplet superconducting order parameters. The superconducting phases showed in this work are in qualitative agreement with experimental results.

Orientador: André Luiz Malvezzi / Banca: Marcio José Martins / Banca: Alexys Bruno Alfonso / O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp / Resumo: Na área de pesquisa em sistemas de elétrons fortemente correlacionados, o modelo das super-redes Hubbard tem sido utilizada para explicar e prever comportamentos de heteroestruturas, como multicamadas magnéticas, que apresentam propriedades diferentes e incomuns, comparadas com as dos sistemas homogêneos análogos, E.G., ordenamentos magnéticos e de carga. Neste contexto, foram estudados nesta dissertação os efeitos da introdução de um novo valor , 'T IND. C', para o parâmetro de hopping de elétron nas interfaces de camadas diferentes da super-rede, ou seja, introduziu-se uma modulação na condução entre as camadas. Variou-se 'T IND. C'entre 0.1T e T, onde T é o parâmetro de hopping entre sítios da mesma camada. Para a lacuna de carga encontramos um comportamento dependente da densidade eletrônica na rede. Em geral, momentos magnéticos locais e a ocupação eletrônica nos sítios, apresentam uma distribuição mais uniforme para 'T IND. C'=0.1T. No entanto, nas densidades onde ocorre um aumento abrupto na lacuna de carga com a diminuição de 'T IND. C', essa uniformidade é mais pronunciada, possivelmente devido a uma comensurabilidade entre a distribuição dos elétrons na cadeia e a estrutura da super-rede. Para as funções de correlação de carga, que foram estudadas através do fator de estrutura, encontramos em alguns casos uma dependência em 'T IND. C' do período do ordenamento correspondente. / Abstract: In the research field of strongly correlated electron systems, the Hubbard superlattice model has been used for explain and predict the behavior of heterostructures, such as magnetic multilayers, whose unusual properties differ from the properties of the analogous homogeneous counterpart. In this context, we have studied here the effects of introducing a new value for the hopping parameter, 'T IND. C', for electrons between different layers, E.G., we introduced a modulation in the electronic conduction between layers. We consider 'T IND. C' in the range 0.1T to T, where T is the hopping parameter for sites inside the layers. For the charge gap, we found a behavior that depends on the electronic density in the lattice. Local magnetic and electronic occupation on sites, generally, show a greater uniformity with decreasing 'T IND. C'. However, for electronic densities where is an abrupt increase in the charge gap for decreasing 'T IND. C', this uniformity is enhanced, probably due to a commensurability between the electronic distribution in the chain and the underlying superlattice structure. For the charge correlation functions, that were studied through their structure factor, we found in some cases a dependency in 'T IND. C' of the correlations oscillation period. / Mestre