We apply a variety of teleseismic methodologies to investigate the upper mantle structure in extensional environments. Using a body wave dataset collected from a regional deployment in the Woodlark Rift, Papua New Guinea, we image anisotropic velocity structure of a rapidly extending rift on the cusp of continental breakup. In the process, we develop a technique for azimuthal anisotropy tomography that is generally applicable to regions of relatively simple anisotropic structure. The Cascadia Initiative ocean bottom seismometer (OBS) deployment provides coverage of an entire oceanic plate in unprecedented detail; we measure attenuation and velocities of teleseisms to characterize the temperature and melt structure from ridge to trench. Our study of shear wave splitting reveals strong azimuthal anisotropy within the Woodlark Rift with fairly uniform fast directions parallel to extension. This observation differs markedly from other continental rifts and resembles the pattern seen at mid-ocean ridges. This phenomenon is best explained by extension-related strain causing preferential alignment of mantle olivine. We develop a simple relationship that links total extension to predicted splitting, and show that it explains the apparent dichotomy in rifts’ anisotropy. Finite frequency tomography using a dataset of teleseismic P- and S-wave differential travel times reveals the upper mantle velocity structure of the Woodlark Rift. A well developed slow rift axis extending >250 km along strike from the adjacent seafloor spreading centers demonstrates the removal of mantle lithosphere prior to complete crustal breakup. We argue that the majority of this rift is melt-poor, in agreement with geochemical results. A large temperature gradient arises from the juxtaposition of upwelled axial asthenosphere with a previously unidentified cold structure north of the rift that hosts well located intermediate depth earthquakes. Localization of upper mantle extension is apparent from the velocity structure of the rift axis and may result from the presence of water following recent subduction. In order to resolve potential tradeoffs between anisotropy and velocity gradients, we develop a novel technique for the joint inversion of ∆Vs and strength of azimuthal anisotropy using teleseismic direct S-waves. This approach exploits the natural geometry of the regional tectonics and the relative consistency of observed splits; the imposed orthogonality of anisotropic structure takes care of the non-commutative nature of multi-layer splitting. Our tomographic models reveal the breakup of continental lithosphere in the anisotropy signal, as pre-existing fabric breaks apart and is replaced by upwelling asthenosphere that simultaneously advects and accrues an extension-related fabric. Accounting for anisotropy removes apparent noise in isotropic travel times and clarifies the velocity model. Taken together, our results paint a detailed and consistent picture of a highly extended continental rift. Finally, we collect a dataset of differential travel time (δT) and attenuation (∆t*) measurements of P- and S-waves recorded on OBS stations that span the Juan de Fuca and Gorda plates. We observe large gradients in ∆t*, with values as high as 2.0 s for S-waves at the ridge axes. Such high values of differential attenuation are not compatible with a purely thermal control, nor are they consistent with focusing effects. We assert that melt, grainsize, and water enhance anelastic effects beneath the ridge. The combination of attenuation and velocity measurements enables us to place quantitative constraints on the properties of the upper mantle in the vicinity of the spreading axis.

As moléculas AHBA (2-Amino-N-hexadecil-benzamida) e DPH (1,6-Difenil-1,3,5- hexatrieno) são sondas fluorescentes com características particulares, comumente utilizadas para monitorar diferentes regiões das bicamadas lipídicas, no entanto, pouco se sabe sobre a mobilidade e dinâmica destas sondas em membranas e quais os principais fatores que influenciam as suas interações com solventes polares e apolares. Esta tese teve por objetivo estudar essas sondas em diferentes ambientes, para ampliar o entendimento de suas estruturas, mobilidade e dinâmicas rotacionais em diferentes solventes e em bicamadas lipídicas. Utilizou-se a técnica de Dinâmica Molecular (DM) para obter as trajetórias das sondas em caixas com diferentes proporções de água e 1,4-dioxano e também nas membranas de POPC (1-palmitoil-2-oleoil-sn-glicerol-3-fosfocolina) e DMPC (1,2-dimiristoil-sn-glicerol-3-fosfocolina). Com as trajetórias geradas, foram analisadas a estrutura, a solvatação e a dinâmica rotacional das sondas em misturas de solventes e membranas modelo. Para as DM em solventes, os resultados indicaram um comportamento atípico das duas moléculas, com a diminuição da interação com a água a medida que diminuía-se a proporção de 1,4-dioxano na caixa. Em membranas, a localização e mobilidade da sonda AHBA apresentaram comportamento semelhante em POPC e DMPC, com os tempos obtidos a partir da curva de autocorrelação rotacional do seu dipolo comparáveis aos medidos pelo experimento de anisotropia de fluorescência resolvida no tempo. Já para o DPH, os resultados em POPC indicaram que a sonda alinha-se paralelamente à superfície da membrana e apresenta muito mais liberdade para se movimentar quando comparada às aos resultados de DM em DMPC, onde a sonda se alinhou paralelamente às caudas dos fosfolipídios e teve uma restrição bem maior para seus movimentos. Os tempos de correlação rotacional do seu dipolo em POPC apresentaram boa concordância com os obtidos experimentalmente. Em contrapartida, os resultados em DMPC mostraram que é preciso mais tempo de DM para comparação entre a correlação rotacional teórica e a experimental, por ser um sistema mais compactado. De qualquer forma, os resultados indicam que a DM é uma técnica promissora para modelagem da dinâmica rotacional de moléculas em membranas. / AHBA (2-Amino-N-hexadecyl benzamide) and DPH (1,6-diphenyl-1,3,5-hexatriene) molecules are fluorescent probes with particular characteristics commonly used to monitor different regions of the lipid bilayers, however, little is known about the mobility and dynamics of these probes in membranes and the main factors that influence their interactions with polar and non-polar solvents. This thesis aimed to study these probes in different environments, to extend the understanding of their structures, mobility and rotational dynamics in different solvents and in lipid bilayers. It was used the Molecular Dynamic (MD) technique to obtain the trajectories of the probes in boxes with different proportions of water and 1,4-dioxane, and also in membranes of POPC (1-palmitoyl-2- oleoy l-sn-glycerol-3 -phosphocholine) and DMPC (1,2-dimyristoyl-sn-glycerol-3-phosphocholine). With the trajectories generated, the structure, solvation and rotational dynamics of the probes were analyzed in solvent mixtures and model membranes. For simulations in solvents, the results indicate an atypical behavior of the two molecules with the decrease of the interaction with water, when decreased the proportion of 1,4-dioxane in the box. In membranes, the location and mobility of AHBA showed similar behavior for on DMPC and POPC, with the decay times obtained from the dipole rotational autocorrelation curve comparable to experimental time-resolved fluorescence anisotropy data. For the DPH in POPC, the results indicated that the probe is aligned parallel to the membrane surface and is much more free to move when compared to simulations in DMPC, where the probe is aligned parallel to the tails of the phospholipids, and had a greater restriction for their movement. The rotational correlation times of their dipole in POPC showed good agreement with those obtained experimentally. On the other hand, the results in DMPC, showed that it needs more time of simulation for comparison between the theoretical and experimental rotational correlation, because it a more compressed system. In any way, the results indicate that MD is a promising technique for modeling the rotational dynamics of molecules in membranes.

Filmes de ligas FePt com uma estrutura quimicamente ordenada Tetragonal de Face Centrada FCT (tipo L1 IND.0) e textura [001] apresentam anisotropia magnética perpendicular, alta coercividade e grande efeito Kerr polar magnetoóptico. Entretanto, filmes completamente ordenados são normalmente obtidos através de um processo de \"sputtering\" com deposições em altas temperaturas do substrato(T IND. S > OU =600 ºC) ou por pós-tratamento térmico em temperaturas maiores que 500 ºC. As pesquisas atualmente em desenvolvimento visam a obtenção dessa estrutura ordenada a temperaturas mais baixas, o que seria mais adequado para aplicações práticas dos filmes. Neste trabalho, procuramos as melhores condições para a preparação de filmes de FePt com a fase ordenada FCT(001) em reduzidas temperaturas. Investigamos a influência do método de deposição, temperatura do substrato, espessura do filme e tipo de substrato sobre o grau de ordem química e textura dos filmes de FePt e, consequentemente, sobre suas propriedades magnéticas. Os filmes finos de ligas Fe IND.xPt IND. x-1(com x = 50 at%) foram preparados por \"Sputtering Magnetron DC\", através de dois diferentes métodos de deposição: pelo usual de codeposição e pelo método de deposiçãO alternada monocamadas atômicas (DAM). Os filmes foram crescidos sobre substratos de SiO IND.2/ Si(100), Si(100) e MgO(100), com e sem uma camada \"buffer\" de Pt ( com espessuras de 50 1 766 nm), sob T IND. s variando de temperatura ambiente a 600 ºC. O \"buffer\" de Pt foi usado para permitir melhores condições para a indução de um crescimento \"epitaxial\" da ordenada fase FCT(001) nos filmes de FePt. Os resultados da caracterização estrutural e magnética realizados através das técnicas de Difração de RAios-X (XRD) e Magnetometria de Amostra Vibrante (VSM) mostram que os substratos de MgO São adequados para induzir um crescimento \"epitaxial\" de filmes de FePt ) com uma estrutura FCT e textura [001]. Entretanto, com o uso de um \"buffer\" de Pt otimizado (com predominante fase FCC(100)), pré-depositado sobre MgO, foram obtifos melhores resultados em termos de \"epitaxia\" conveniente para o ordenamento da estrutura cristalina, para os filmes de FePt preparados por ambos os métodos de deposição. Os resultados mostram também que o efeito de um crescimento \"epitaxial\" induzido varia com a espessura do filme. Em relação ao método de deposição, os resultados revelam a maior eficiência de método DAM em comparação com o métodos de codeposição para a preparação de filmes de FePt com a fase FCT(001), em temperaturas reduzidas (T IND.s < OU = 400ºC). Com o uso do método DAM, foi possível a obtenção da fase ordenanda FCT(001) em filmes de FePt crescidos diretamente sobre o MgO em T IND. s = 400ºC. Para filmes de FePt crescidos sobre Pt/MgO, a formação da fase FCT(001) foi verificada em T IND.s = 200ºC e um alto grau de ordenamento químico (S = 0,88) em T IND. s = 400ºC. Estudos de Espectroscopia de Absorção de Rios-X (XAS) também foram realizados. / FePt alloy films, with a chemically ordered face-centered-tetragonal FCT (type LI IND.0) structure and [001] texture, present perpendicular magnetic anisotropy, high coactivity and large polar magneto-optical Kerr effect. However, completely ordered films are usually obtained either by sputtering process at high substrate temperatures (T IND.s MAIOR IGUAL A 600°C) or by postanneling treatment at temperatures higher than 500°C. For technological purposes the preparation temperatures has to be as low as possible. In this work we have searched the more adequate conditions to preparation of FePt films with ordered FCT(001) phase at reduced temperatures. We have investigated the influence of deposition methods, substrate temperature, thickness of film, and type of substrate on the degree of the chemical ordering and preferred texture of FePt films and, consequently, on their magnetic properties. The Fe IND.xPt IND.1-x alloy thin films (with x SEMELHANTE A 50 at%) were prepared by DC Magnetron Sputtering, via two different deposition methods: a conventional code position method and an alternate monatomic layer (DAM) deposition method. The films were grown on SiO IND.2/Si (100), Si (100) and MgO (100) substrates, with and without a Pt buffer layer (thickness ranging from 50 to 76 nm), at T IND.s varying from room temperature to 600°C. The Pt buffer layer was used for obtaining better conditions to the induction of an epitaxial grown of FePt films with the ordered FCT(001) phase. The results of structural and magnetic characterization performed by X-ray diffraction (XRD) and vibrating sample magnetometry (VSM) show that the MgO substrates are adequate to induce an epitaxial growth of FePt films with a FCT structure and [001] texture. However, with the use of an optimized Pt FCC(100) buffer layer pre-deposited on MgO, the best conditions to an epitaxial induced growth were obtained, by both deposition methods. The results show also that the quality of the epitaxial induced growth depends on the thickness of the film. In relation to the deposition method in comparison to the code position method for preparation of FePt FCT(001) films, at reduced temperatures (T IND.s MENOR IGUAL A 400°C). With the use of the DAM method it was possible to obtain the ordered FCT(001) phase in the FePt film grown directly on MgO, at T IND.s = 400°C. For FePt film grown on Pt/MgO, the formation of the FCT(001) phase was verified at T IND.s = 200°C, and high degree of chemical order (S=0,88) was obtained at T IND.s = 400°C. X-ray Absorption Spectroscopy (XAS) studies also were done.

The purpose of this work was to understand the influence of materials and construction on football performance. Two main areas identified as needing further work were post-impact rebound deviation and acoustic response. To further investigate these areas, football materials were tested in a lab with different loading scenarios and the resulting data was used in various characterisation methods to help define finite element models. The finite element models were used to efficiently explore a variety of material and construction variations. Acoustic data for a range of balls was collected in an anechoic chamber and advanced coupled Eulerian-Lagrangian simulations were developed to visualise the mode shapes of internal resonances.

Neste trabalho foram estudados os processos de migração e transferência de energia em derivados de polifluoreno, de estrutura totalmente conjugada e de conjugação confinada. A dinâmica de estado excitado dos derivados PF-BNI, PFOPPV e PFPPV foi estudada em solução diluída de diferentes solventes através de espectroscopia eletrônica de alta resolução temporal. O derivado PF-BNI, contendo N-(2-benzotiazol)-1,8-naftalimida (BNI) como terminador da cadeia de poli(9,9\'dioctilfluoreno), foi sintetizado pela rota de Yamamoto. O material apresenta alto rendimento quântico de fluorescência e suas propriedades de emissão são moduladas pela polaridade do solvente. As medidas de fluorescência resolvida no tempo mostraram a migração do exciton singlete ao longo da cadeia polimérica e a formação de um estado excitado de transferência de carga intracadeia (ICCT). Os derivados PFOPPV e PFPPV são copolímeros de fluoreno contendo unidades fluoreno-vinileno-fenileno no segmento cromofórico. No PFOPPV o segmento cromofórico é confinado entre segmentos alifáticos (-(CH2)8-) flexíveis, no PFPPV a cadeia principal é totalmente conjugada. A dinâmica de estado excitado dos derivados, PFOPPV e PFPPV, é caracterizada pela presença de segmentos cromofóricos contendo isômeros cis e trans. No PFOPPV, a sua estrutura segmentada permite a transferência de energia entre os segmentos cromofóricos, via interações dipolo-dipolo. A transferência acarreta a depolarização da emissão de fluorescência. No caso do PFPPV a migração de energia ocorre em menos de 20 ps e o decaimento de fluorescência decorre da emissão de segmentos contendo isômeros cis e trans, já na condição estacionária. / This work reports the study of energy transfer and migration processes in fully conjugated and segmented polyfluorene derivatives. The excited-state dynamics of the derivatives, PF-BNI, PFOPPV and PFPPV was studied in diluted solution of different solvents by means of ultrafast time-resolved spectroscopy. Poly(9,9\'-dioctylfluorene) end-capped with N-(2-benzothiazole)-1,8-naphthalimide, named PF-BNI, was prepared via Yamamoto-coupling reaction. This derivative is a highly fluorescence material with emission modulated by solvent polarity. Time-resolved fluorescence measurements showed the singlet exciton migration through the polymer backbone and the formation of an intrachain charge transfer excited-state (ICCT). PFOPPV and PFPPV are both fluorene copolymers containing fluorene-vinylene-phenylene moieties in the backbone. Whereas the PFPPV backbone is fully conjugated, the chromophore segment in PFOPPV backbone is confined between aliphatic (-(CH2)8-) flexible segments. The excited-state dynamics of both copolymers is characterized by the presence of conjugated moieties containing cis and trans isomers. The segmented structure of PFOPPV allows the resonant energy transfer between the chromophores, which is provided by dipole-dipole interactions. The energy transfer process leads to the depolarization of PFOPPV fluorescence emission. For PFPPV the energy migration occurs in less than 20 ps and the fluorescence decay is ascribed to the emission of chromophore segments containing cis and trans, already in a photostationary condition.

La motivation principale de cette thèse est d’être capable de prédire précisément la rupture d’une tôle d’aluminium anisotrope avec un chemin de déformation linéaire et non-linéaire. Dans le cas présent, le matériau utilisé est l’AA6016 et le chemin de déformation considéré est traction uniaxiale suivie de pliage jusqu’à rupture. Deux approches sont appliquées et comparées, l’une utilise la plasticité associée (AFR) et l’autre la plasticité non-associée (NAFR). Dans le but d’obtenir une bonne représentation de l’anisotropie en AFR, un critère de plasticité très flexible est utilisé : Yld2004-18p. L’identification des paramètres est faite avec une approche inverse qui consiste à minimiser itérativement l’écart entre les résultats numériques et expérimentaux. Une fois que l’écart arrête d’évoluer (minimum local) ou atteint une valeur prédéterminé e assez faible, l’optimisation s’arrête et les derniers paramètres mis à jour sont enregistrés. En corrélation avec des travaux de recherche plus récents, un modèle NAFR est utilisé pour modéliser l’anisotropie du matériau. Il combine deux critères de plasticité qui sont utilisés pour la surface d’écrouissage et le potentiel plastique. Leurs paramètres sont identifiés grâce aux ratios de contraintes et aux valeurs r obtenues expérimentalement. Concernant la rupture, des modèles découplés macroscopiques sont étudiés : un critère Hosford-Coulomb modifié et un critère basé sur DF2014. Ces deux critères prennent en compte les trois invariants du tenseur des contraintes pour prédire la déformation équivalente à rupture mais sont identifiés avec différentes méthodes pour prendre en compte l’anisotropie de la rupture. Enfin, des résultats sur des instabilités plastiques obtenus avec un modèle NAFR sont présentés dans le but de prouver les possibilités de cette approche comparée à une approche AFR. / The main motivation of this thesis is to be able to predict accurately the fracture of an anisotropic aluminium alloy thin sheet under linear and non-linear strain paths. In the studied case, the material used is the AA6016 and the non-linear strain path considered is uniaxial tension followed by free bending until fracture. Two approaches are considered and compared which respectively use the associated flow rule (AFR) and the non-associated flow rule (NAFR). In order to obtain a good representation of the high anisotropy of the material in AFR, a very flexible yield criterion is used: Yld2004-18p. The identification of its parameters is done with an inverse approach consisting of iteratively minimizing the gap between numerical and experimental results. Once this gap stops evolving (local minimum) or reaches a low enough pre-determined value, the optimization stops and the last updated parameters are saved. In correlation with more recent research work, a NAFR model is used to model the anisotropy of the material. It combines two different yield functions that are used for the yield surface and the plastic potential. Their parameters are identified by using stress ratios and rvalues measured experimentally. Concerning the fracture, uncoupled macroscopic models are studied: a modified Hosford-Coulomb and a DF2014 based criteria. Both these criteria take into account the three invariants of the stress tensor to predict the equivalent strain to fracture but their parameters are identified with different methods to take into account the anisotropy of the fracture. Finally, results on plastic instabilities obtained with a NAFR model are presented in order to prove the possibilities of this approach compared to AFR.

This dissertation will focus on the volatile compounds released upon the burning of incense which are numerous and varied. The first part of this dissertation is the gas chromatography-mass spectral (GC-MS) analysis of burning incense collected via solid phase microextraction (SPME) with the aim of developing a library of compounds found in incense as used in the Orthodox church. The second part of this dissertation has the aim of developing a method for forming oleic acid bilayer vesicle membranes and a fluorescence spectroscopy method by which the reactivities of these vesicles can be analyzed. These reactivities include permeability, fluidity, aggregation, and fusion of the membranes. One family of the volatile compounds found in incense are the terpenes and terpenoids. The reactivity of the terpenes and terpenoids found in incense will be analyzed using the oleic acid vesicles with the hypothesis that terpenes of the same structural groups will act similarly on oleic acid vesicle membranes and these reactivities can be related to mechanistic interactions.

Les matériaux supraconducteurs présentent des propriétés physiques et géométriques particulières qui exigent des approches de modélisation spatio-temporelle fines, où les méthodes classiques trouvent rapidement leurs limites en termes de convergence, de précision et de temps de calcul. Ce dernier peut être très conséquent, ce qui est incompatible avec les problèmes de dimensionnement et d’optimisation. Dans ce contexte, ce travail a pour objectif de développer des approches de modélisation multiphysique rapides pour le dimensionnement et l’optimisation des systèmes à base de supraconducteurs. Un intérêt particulier est porté pour les méthodes intégrales. Les verrous scientifiques à lever, qui constituent également l’originalité du travail, résident dans l’intégration des lois de comportement E(J) des supraconducteurs dans les schémas numériques de ce type de méthodes. Dans ce travail on développe un modèle numérique afin d’étudier la distribution de la densité de courant et d’estimer les pertes AC dans les supraconducteurs à haute température (HTS). Le modèle développé est basé sur une formulation intégro-différentielle en termes de potentiel vecteur électrique dans les deux domaines fréquentiel et temporel. Une campagne de test est menée afin de valider et de bien cerner les possibilités offertes et les limites de cette approche pour la modélisation des supraconducteurs. / Superconducting materials have particular physical and geometric properties that require spatial-temporal modeling approaches fines, where conventional methods quickly reach their limits in terms of convergence, precision and computational time. The latter can be very consistent, which is incompatible with the design and optimization problems. In this context, this work aims to develop rapid multiphysics modeling approaches for the design and optimization of superconductor-based systems. Particular attention is paid to the integral methods. Scientific obstacles to overcome, which also constitute the originality of the work lies in the integration of behavior laws E (J) of superconducting digital patterns of such methods. A numerical model is developed for a rapid computation of eddy currents in multifilamentary high temperature superconductive (HTS) for the evaluation of AC losses. The developed model is based on an integro-differential formulation in terms of the electric vector potential in the frequency and temporal domains. A test campaign is conducted to validate and clearly identify the possibilities and limitations of this approach for modeling superconductors.

A liga de alumínio AA 5182 é utilizada para a fabricação de tampas de latas de bebidas, além de aplicada também no setor automotivo. Essa liga tem elevada resistência mecânica devido à presença de Mg. O presente trabalho visa estudar os efeitos da anisotropia desta liga laminada a frio e submetida a diferentes tipos de tratamento de estabilização e pintura. Nesse estudo, foram comparadas amostras com teores de magnésio e cobre variando dentro da faixa dessa liga nas condições: laminada a frio, pintada e tratada termicamente a 150 °C / 1 hora, 165 °C / 1 hora e a 180 °C / 1 hora. Foram analisadas e comparadas a microestrutura, tamanho médio de grão, dureza e propriedades mecânicas nas condições citadas. Observou-se que não há alteração nas partículas de segunda fase em nenhuma das condições testadas. As propriedades mecânicas do material pintado são semelhantes às do material tratado termicamente a 150 °C / 1 hora. Para todas as condições testadas, as propriedades mecânicas reduzem em 3 a 6% a 45° do sentido de laminação e as propriedades dos materiais tratados termicamente ou pintado são reduzidas em 4 a 10% quando comparadas às amostras na condição laminado a frio. Para as duas amostras, observou-se que os efeitos da anisotropia são reduzidas com o aumento da temperatura de tratamento. / The aluminum alloy AA 5182 is used for the production of lids for beverage cans, besides this it is also applied at the auto market. This alloy has an enhanced resistance due to Mg presence. This work aim to evaluate the effect on the anisotropy of this alloy cold rolled submitted to different heat treatments and coated. At this study it was compared samples with different Mg and Cu content varying within the specification of the alloy at the following conditions: cold rolled, coated, and heat treated at 150 °C / 1 hour, 165 °C / 1 hour; 180 °C / 1 hour. It was analyzed and compared the microstructure, average grain size, hardness and mechanical properties on the conditions mentioned. It was not observed any differences at the second phase particles at this conditions. The mechanical properties of the painted material are similar to the heat treated at 150 °C / 1 hour. For all the conditions tested, the mechanical properties decrease around 3 - 6% at 45° of the rolling direction and the mechanical properties of the heat treated or painted material decrease around 4 - 10% compared to the cold rolled. For both samples it was observed that the anisotropy reduces with the increase of the temperature of the heat treatment.

The continued progress of modern information technology relies on understanding the influence of magnetic anisotropy on magnetic thin films. In this work, two sources of magnetic anisotropy are examined in two different soft ferromagnets: a uniaxial anisotropy induced during the fabrication of Ni80Fe20 and exchange anisotropy, or exchange bias, which occurs at the interface of Ni77Fe14Cu5Mo4/Fe50Mn50 bilayer. A home-built Magneto-optical Kerr effect magnetometer is used to measure the magnetic response of the soft ferromagnetic films and details of its construction are also discussed. A simple model of uniaxial anisotropy is described, then applied, to the uniaxial NiFe film and deviations from the model are critically analyzed. The exchange bias and coercive fields of NiFeCuMo/FeMn are reported for the first time and studied as a function of buffer layer material. The influence of the different buffer layer materials on the magnetization response of the bilayer is explained from a structural standpoint.