Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-12-22T12:37:32Z No. of bitstreams: 1 josielcarlosdesouzagomes.pdf: 11267373 bytes, checksum: 393a01f57f4f5afaaf46890b84f4a7ac (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-12-22T12:42:22Z (GMT) No. of bitstreams: 1 josielcarlosdesouzagomes.pdf: 11267373 bytes, checksum: 393a01f57f4f5afaaf46890b84f4a7ac (MD5) / Made available in DSpace on 2016-12-22T12:42:22Z (GMT). No. of bitstreams: 1 josielcarlosdesouzagomes.pdf: 11267373 bytes, checksum: 393a01f57f4f5afaaf46890b84f4a7ac (MD5) Previous issue date: 2015-02-26 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A nanotecnologia é uma área de estudo promissora e que nos mostra resultados bastante surpreendentes. Amostras magnéticas (Cobalto e liga de Permalloy (Ni81Fe19), por exemplo) em escala nanométrica, têm como aplicabilidade importante a gravação magnética devido à crescente demanda por meios de gravação cada vez mais rápidos e de alta capacidade de armazenamento. Para determinados tamanhos de nanofios, observa-se a presença de domínios magnéticos e paredes de domínios do tipo vórtice ou transversal que podem ser transportadas para diferentes regiões sem deformação. Pode-se usar tais paredes como bit de informação mas, para isso, precisa-se conhecer com detalhes o comportamento dessas paredes em diversas situações. Neste presente trabalho utilizamos simulações numéricas para estudar o comportamento da magnetização em nanofios retangulares (nanofitas) de Permalloy-79, que apresentam parede de domínio transversal entre domínios “head-to-head”. Utilizamos nestas simulações um modelo no qual os momentos magnéticos interagem através da interação de troca e a interação dipolar. Embora a maioria dos trabalhos encontrados utilizem campo magnético para mover a parede, optamos por aplicar corrente de spin-polarizado na direção do nanofio devido ao fato de ser mais prático de ser produzido. A dinâmica do sistema é regida pelas equações de Landau-Lifshitz-Gilbert e a atuação da corrente é introduzida nessas equações. Fizemos uma abordagem teórica na qual pode-se mostrar como esta equação de Landau-Lifshitz-Gilbert para aplicação de corrente foi obtida. A integração da equação de Landau-Lifshitz-Gilbert é feita utilizando o método de Runge-Kutta e de Predição-Correção. Baseado nessas teorias, escrevemos um programa na linguagem Fortran-90 para realizar as simulações. Em nossos resultados observamos o comportamento da velocidade da parede de domínio em função do tempo e da densidade de corrente. Comparamos estes resultados com a bibliografia. / Nanotechnology is a promising field of study and show us pretty amazing results. Magnetic samples (Cobalt and alloy Permalloy (81NiFe19), for example) at the nanometer scale, have as important applicability the magnetic recording due to the growing demand for recording media ever faster and high storage capacity. For certain sizes of nanowires, it is observed the presence of magnetic domains and vortex domain walls or transverse domain wall which can be transported to different regions without deformation. It can use such walls as bit of information, but for that it is necessary to know in detail the behavior of these walls in various situations. In this work we used numerical simulations to study the behavior of the magnetization in rectangular nanowires (nanostrip) of Permalloy-79, which have transverse domain wall between domains "head-to-head."We used in these simulations a model in which the magnetic moments interact through the exchange interaction and the dipolar interaction. Although most studies found use magnetic field to move the wall, we decided to apply spin-polarized current toward the nanowire due the fact that it is more practical to be produced. The dynamics of the system is governed by the equations of Landau-Lifshitz-Gilbert and the current performance is introduced in these equations. We made a theoretical approach in which you can show how this equation of Landau-Lifshitz-Gilbert for applying current was obtained. The integration of the equation of Landau-Lifshitz-Gilbert is done using the Runge-Kutta and Prediction-Correction methods. Based on these theories, we wrote a program in Fortran-90 language to perform the simulations. In our results we observed the behavior of the domain wall velocity as a function of time and current density. We compare these results with the literature.

Made available in DSpace on 2016-08-17T13:54:31Z (GMT). No. of bitstreams: 1 Dissertacao Maria Clea.pdf: 3193747 bytes, checksum: 21003fc9fd868b7373cc1419846a1fa0 (MD5) Previous issue date: 2012-08-31 / L imaginaire et le symbolisme dans la Littérature infantile et juvénile et sa contribution sur la formation du lecteur. Étude de nature théorique ayant pour but d analyser l imaginaire à partir de la symbologie du mot et de l illustration, dans la littérature infantile et juvénile des oeuvres choisies. Pour la recherche, ainsi que sa contribution pour la formation du lecteur, considérant quelques aspects de la théorie de l imaginaire de Gilbert Durand. On y présente un panorama sur le cursus, la lecture et la littérature infantile et juvénile dans le cadre scolaire, en les situant comme des outils qui contribuent à la formation du sujet réflexif et créatif. On y analyse l imaginaire dans le contexte éducationnel auprès des paradigmes émergents dans les sciences humaines et sociales. On cherche à prendre comme base la Théorie de l imaginaire dans les oeuvres de Durand, surtout Les Structures Anthropologiques de l Imaginaire : introduction à l archétypologie générale (2002), et des auteurs qui sont dans la même ligne paradigmatique. On y analyse les oeuvres Menina Bonita do Laço de Fita et Bisa Bia, Bisa Bel, de Ana Maria Machado, sous l optique de l Herméneutique Symbolique, une méthodologie qui a permis de faire un relevé des images sous-jacentes dans le récit (texte et illustration) des histoires. On conclut que le caractère créatif, rêveur et épiphanique de la littérature infantile et juvénile de Ana Maria Machado s intègre à la théorie de l imaginaire chez Durand dans la mesure où Il possibilite de mettre en marche l imagination créatrice, et l utilisation de cette littérature à l école sans « prétextes », juste en laissant surgir librement le symbolisme présent dans le récit, peut contribuer à la construction d un sujet plus sensible aux questions du monde qui l entoure. / Imaginário e simbolismo na Literatura infantil e juvenil e sua contribuição na formação do leitor. Estudo de natureza teórica que objetiva analisar o imaginário a partir da simbologia da palavra e da ilustração na literatura infantil e juvenil nas obras selecionadas para a pesquisa, bem como sua contribuição para a formação do leitor considerando alguns aspectos da teoria do imaginário de Gilbert Durand. Apresenta um panorama sobre currículo, leitura e literatura infantil e juvenil no ambiente escolar situando-os como instrumentos que contribuem à formação do sujeito reflexivo e criativo. Relaciona o imaginário no contexto educacional junto aos paradigmas emergentes nas ciências humanas e sociais. Busca fundamentar a Teoria do Imaginário nas obras de Durand especialmente As Estruturas Antropológicas do Imaginário: introdução à arquetipologia geral (2002) e autores que transitam no mesmo solo paradigmático. Analisa as obras Menina Bonita do Laço de Fita e Bisa Bia, Bisa Bel de Ana Maria Machado sob a lupa da Hermenêutica Simbólica, metodologia que possibilitou realizar o levantamento das imagens subjacentes na narrativa (texto e ilustração) das histórias. Conclui que o caráter criativo, fantasioso e epifânico da literatura infantil e juvenil de Ana Maria Machado integra-se à teoria do imaginário em Durand à medida que possibilita o exercitar da imaginação criadora e, o uso dessa literatura na escola sem pretextos apenas deixando fluir o simbolismo presente na narrativa, pode contribuir para a construção de um sujeito mais sensível às questões do mundo que o cerca.

L'amélioration des techniques de dépôts et l’évolution de la compréhension de la physique de la matière condensée a conduit à la découverte de phénomènes nouveaux en électronique de spin (spintronique). En particulier, le retournement de l’aimantation par couple de transfert de spin et couple spin-orbite, ainsi que le développement de dispositifs basés sur la propagation d’ondes de spin ont fait de l’amortissement magnétique de Gilbert un paramètre central pour les futures technologies de stockage et de traitement de l’information. Dans cette étude, la prédiction de valeurs très faibles d’amortissement dans les alliages d’Heusler demi métaux magnétiques Co2MnZ est expérimentalement observée et directement corrélée à la structure électronique sous-jacente. En effet, en substituant l’élément Z dans des couches minces monocristallines de haute qualité de Co2MnZ (Z= Al, Si, Ga, Ge, Sn, Sb) faites par épitaxie par jet moléculaire, les propriétés électroniques telles que le gap de spin minoritaire, la position du niveau de Fermi et la polarisation en spin peuvent être accordées et leurs conséquences sur la dynamique de l’aimantation sont analysées. Les résultats expérimentaux nous permettent de comprendre la relation existante entre la structure électronique mesurée et la valeur d’amortissement magnétique, ainsi que de les comparer aux calculs ab initio. Les valeurs d’amortissement entre 4.1 x10-4 et 9 x10-4 pour Co2MnSi, Co2MnGe, Co2MnSn et Co2MnSb sont les plus petites valeurs jamais reportées pour des couches conductrices et constituent une preuve expérimentale qui confirme les prédictions théoriques sur ces alliages d’Heusler demi métaux magnétiques. Ensuite, la relation entre l’amortissement magnétique de Gilbert et le temps de désaimantation ultra-rapide induit par pulse laser dans la série d’alliages quaternaires Co2MnSixAl1-x à polarisation en spin variable est étudiée. Cette partie vise à vérifier des modèles théoriques qui essaient d’unifier ces deux quantités vivant sur des échelles de temps différentes. Finalement, les propriétés structurales et magnétiques de super réseaux Mn3Ga/Co2YZ sont étudiées dans le but de combiner un amortissement de Gilbert très faible, un gap de spin minoritaire ainsi que l’aimantation perpendiculaire aux plans des couches, une caractéristique indispensable pour des dispositifs à faible consommation d’énergie. / Improvements in thin film elaboration methods and a deeper understanding of condensed matter physics have led to new exciting phenomena in spin electronics (spintronics). In particular, magnetization reversal by spin-orbit and spin-transfer torque as well as the development of spin waves based devices have placed the Gilbert magnetic damping coefficient as a key parameter for future data storage and information processing technologies. The prediction of ultralow magnetic damping in Co2MnZ Heusler half-metal magnets is explored in this study and the damping response is shown to be linked to the underlying electronic structure. By substitution of the Z element in high quality Co2MnZ (Z=Al, Si, Ga, Ge, Sn and Sb) epitaxial thin films grown by molecular beam epitaxy, electronic properties such as the minority-spin band gap, Fermi energy position in the band gap, and spin polarization can be tuned and the consequences for magnetization dynamics analyzed. Experimental results allow us to directly explore the interplay of spin polarization, spin gap and Fermi energy position, with the magnetic damping obtained in these films (together with predictions from ab initio calculations). The ultralow magnetic damping coefficients measured in the range from 4.1 x10-4 to 9 x10-4 for Co2MnSi, Co2MnGe, Co2MnSn and Co2MnSb are the lowest values ever reported in conductive layers and offer a clear experimental demonstration of theoretical predictions on half metal magnetic Heusler compounds. Then, the relation between the Gilbert damping and the ultrafast demagnetization time in quaternary Co2MnSixAl1-x compounds with a tunable spin polarization is analyzed. This way, it is possible to confront theoretical models unifying those two quantities that live in different timescales. Finally, structural and magnetic properties of Mn3Ga/Co2YZ Heusler superlattices are investigated in order to combine ultralow Gilbert damping coefficient, minority spin band gap and perpendicularly magnetized heterostructures, another requirement for low energy consumption devices. Through the present work, we aim to prove that Heusler compounds provide an excellent playground to study fundamental magnetism and offer a pathway for future materials design.

In the Swedish Armed Forces there is a discussion whether the officer education is teaching the right things. The right things are often considered to be practical skills. However, the Swedish Defense University mostly teaches theoretical analyzing and critical approach. This study focuses on how well this approach is received by the Armed Forces, with their view of the officer needing practical skills. It does so through a survey sent to the officers in the ground forces, asking how the newly graduated second lieutenants are perceived by the organization. The result in this survey shows that this focus on theoretical knowledge has been perceived by the second lieutenant and the officers in the organization have trust in the graduates, both in character and knowledge. However, the lack of practical knowledge is considered dire and the first time after graduation is primarily focused on becoming an instructor which is considered the NCOs specialty. Because of this discrepancy the second lieutenants may have a hard time translating the theoretical knowledge to practical.

Indiana University-Purdue University Indianapolis (IUPUI) / This essay explores a broad range of literary works that treat long-term grief as a natural response to the death of a child. Literary examples show gaps in the medical and social sciences’ considerations of grief, since these disciplines judge bereaved mothers’ grief as excessive or label it bereavement disorder. By contrast, authors who employ the ancient storyline of child death illuminate maternal grieving practices, which are commonly marked with a vigilance that expresses itself in wildness. Many of these authors treat grief as a forced pilgrimage, but question the possibility of returning to a previous state of psychological balance. Instead, the mothers in their stories and poems resist external pressure for closure and silence and favor lasting memory. Harriet Beecher Stowe, in Uncle Tom’s Cabin, and Emily Dickinson, in letters to bereaved mother Susan Gilbert Dickinson and in the poetry included in these letters, represent maternal child loss as compelling a movement into a new state and emphasize the lasting pain and disruption of this loss.

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Nous avons fait l'adaptation cinématographique du roman La Manne Bleue qui a été qualifié par plusieurs critiques, lors de sa parution, de roman-reportage ou reportage romancé. Notre travail exhaustif de réécriture a permis d'en faire un film de fiction. Nous nous sommes servi de la méthode d'adaptation de Monsieur François Baby intitulée Du littéraire au cinématographique, problématique de l'adaptation. Cet outil de base nous a aidé à analyser l'oeuvre romanesque et à en dégager une stratégie d'adaptation. De là est né un scénario pour long métrage de fiction, qui veut mettre l'accent sur la tension dramatique vécue en contexte de cueillette de bleuets. Le processus d'adaptation cinématographique mis en oeuvre dans ce mémoire démontre bien qu'il s'agit d'une technique particulière. L'application théorique et méthodologique en cause devrait donc permettre, à sa manière, d'explorer plus à fond le champ de recherche des études de transposition cinématographique. / Québec Université Laval, Bibliothèque 2018

The April 1837 debut of tenor Gilbert-Louis Duprez at the Paris Opéra sparked uproarious applause and inspired a new group of tenors with a different vocal technique from tenors of the previous generation. Whereas previous tenors of the nineteenth century sang in a graceful, light, and flexible style that complemented the operatic compositions of Gluck, Rossini, and Bellini, Duprez sang in a powerful, forceful voice that brought new dramatic fervor to the existing repertoire of French Grand Opera. Duprez’ stentorian vocal representations of Arnold in Rossini’s Guillaume Tell and Robert in Meyerbeer’s Robert le diable, among others, inspired composers to write more prominent and dramatic tenor roles, eventually leading to the tenor roles in the operas of Verdi and Wagner. Duprez’ 1837 debut also marked the end of Adolphe Nourrit’s eleven-year reign as the sole leading tenor at the Paris Opéra. Threatened by the prospect of competition, Nourrit eventually left France for Italy in pursuit of the same vocal technique that insured Duprez’ fame. Nourrit studied with Donizetti and debuted at the Teatro di San Carlo in Naples, but grew impatient with his slow progress, disliked the sound of his new voice, and tried to turn back to his old way of singing. He failed to do so and lost his high notes, as well as his head voice. Nourrit’s pursuit ended in 1839 as he threw himself from the third floor of his residence, his voice, his health, and his psyche all in shambles. The shift in vocal technique involved a lowered laryngeal position, a raised velum, and a greater use of chest voice muscles in the higher ranges of the tenor voice. The resulting voix sombrée or “closed” or “covered” timbre, offers distinct hygienic and acoustic advantages, resulting in healthier vocalization and greater amplification of the upper harmonics of the voice. The voix sombrée allows the singer to sing at higher pitch levels with lower levels of tension in the vocal folds and the harmonics from the voice source are greatly enhanced at 2500-3200 Hz, the “singer’s formant,” the range at which the human ear is most sensitive. By reviewing the writings of singers, teachers, and critics of the early nineteenth century and comparing their descriptions of singers’ voices, and then comparing those descriptions with modern studies on the physiology and acoustics of the voice, one can paint a more informed picture concerning the nature and sound of the voices of Nourrit and Duprez. Analysis seems to show that Adolphe Nourrit utilized the lighter vocal production typical of earlier Rossinian tenors, combined with the nasal vocalization of French singers of the early 1800’s. His technique included a low velum, raised larynx, and a pure head voice in the high register. Conversely, Duprez sang with a lowered larynx and a larger degree of chest voice function in his high register. Duprez also incorporated Italian ideals of emphasis on the sound of the voice, rather than the French tendency to emphasize the words. Duprez’s innovations, based in the vocal technique already being used in Italy in the early 1830’s, propelled the voix sombrée technique into the French spotlight, and led to the eventual globalized use of the technique in the opera world.

Understanding magnetization reversal is very important in designing high density and high data transfer rate recording media. This research has been motivated by interest in developing new nonvolatile data storage solutions as magnetic random access memories - MRAMs. This dissertation is intended to provide a theoretical analysis of static and dynamic magnetization switching of magnetic systems within the framework of critical curve (CC). Based on the time scale involved, a quasi-static or dynamic CC approach is used. The static magnetization switching can be elegantly described using the concept of critical curves. The critical curves of simple uncoupled films used in MRAM are discussed. We propose a new sensitive method for CC determination of 2D magnetic systems. This method is validated experimentally by measuring experimental critical curves of a series of Co/SiO2 multilayers systems. The dynamics switching is studied using the Landau-Lifshitz-Gilbert (LLG) equation of motion. The switching diagram so-called dynamic critical curve of Stonerlike particles subject to short magnetic field pulses is presented, giving useful information for optimizing field pulse parameters in order to make ultrafast and stable switching possible. For the first time, the dynamic critical curves (dCCs) for synthetic antiferromagnet (SAF) structures are introduced in this work. Comparing with CC, which are currently used for studying the switching in toggle MRAM, dCCs show the consistent switching and bring more useful information on the speed of magnetization reversal. Based on dCCs, better understanding of the switching diagram of toggle MRAM following toggle writing scheme can be achieved. The dynamic switching triggered by spin torque transfer in spin-torque MRAM cell has been also derived in this dissertation. We have studied the magnetization's dynamics properties as a function of applied current pulse amplitude, shape, and also as a function of the Gilbert damping constant. The great important result has been obtained is that, the boundary between switching/non-switching regions is not smooth but having a seashell spiral fringes. The influence of thermal fluctuation on the switching behavior is also discussed in this work.

La famille des alliages d'Heusler regroupe plusieurs composés considérés comme étant des candidats de choix pour être intégrés en tant qu'électrode magnétique dans des dispositifs d'électronique de spin performants. Les plus intéressants de ces alliages présentent en effet des températures de Curie élevées, une demi-métallicité théorique ainsi qu'un faible coefficient d'amortissement de Gilbert. Expérimentalement, les résultats obtenus sont cependant généralement moins probants que ceux annoncés numériquement. La première partie de cette thèse est donc consacrée à l'étude ab initio d'hypothèses usuellement utilisées pour expliquer les différences entre mesures expérimentales et résultats théoriques. Des calculs basés sur la théorie de la fonctionnelle de la densité ont été effectués pour comprendre l'impact de défauts structuraux (désordres chimiques partiels, déformations tétragonales, lacunes) sur les propriétés électroniques et magnétiques statiques et dynamiques d'alliages full-Heusler massifs à base de Co (Co2MnSi, Co2MnSn, Co2MnAl et Co2FeAl). Dans la seconde partie de cette thèse nous proposons d'étudier, avec les mêmes outils numériques, les caractéristiques physiques d'hétérostructures "tout-Heusler" prometteuses pour l'électronique de spin et rares dans la littérature. Nous nous sommes concentrés sur les variations des propriétés électroniques aux voisinages des interfaces demi- métal/isolant (Fe2TiSi/Co2MnSi, CoTiAs/Co2MnSi) ou demi-métal/métal (Fe2VAl/Co2MnSi, RhNiSi/Co2MnSi) composant les multicouches étudiées. Les résultats obtenus démontrent l'intérêt certain de ces structures pour des applications en électronique de spin, telles que les vannes de spin ou les jonctions tunnel magnétiques. / The Heusler alloy family contains several compounds considered to be prime candidates to be integrated as magnetic electrode into high-?performance spintronic devices. Some of these alloys indeed exhibit high Curie temperatures, have been predicted theoretically to be half-?metallic, and display a low Gilbert damping parameter. Nevertheless, the experimental results are generally less convincing than those reported numerically. The first part of this thesis is devoted to the ab initio study of hypotheses that are usually used to explain the differences between experimental and theoretical results. Calculations, based on the density functional theory, are then used to understand the impact of structural defects (partial chemical disorders, tetragonal deformation, vacancies) on the static and dynamic electronic and magnetic properties of Co-?based bulk full-Heusler alloys (Co2MnSi, Co2MnSn, Co2MnAl et Co2FeAl). In the second part of this thesis we propose to study, with the same numerical tools, the physical characteristics of "all-Heusler" heterostructures promising for spintronics and rare in the literature. We have focused on the variations of electronic properties in the vicinity of the "half-metal/insulator" (Fe2TiSi/Co2MnSi, CoTiAs/Co2MnSi) or "half-metal/non-magnetic metal" (Fe2VAl/Co2MnSi, RhNiSi/Co2MnSi) interfaces composing the studied multilayers. The obtained results highlight the interest of these structures for spintronic devices such as spin valves or magnetic tunnel junctions.