Dissertations / Theses on the topic 'Cook Co'
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Grant, Carl L. "Sunday school curriculum materials development blending theory and technology /." Theological Research Exchange Network (TREN), 1993. http://www.tren.com.
Full textAppelman, Jaco H. "Governance of global interorganizational tourism networks : changing forms of co-ordination between the travel agency and aviation sector = Coordinatie van mondiale interorganisationele toerisme netwerken : veranderende vormen van coordinatie tussen reisagenten en de luchtvaart sector /." Rotterdam : Erasmus Research Institute of Management (ERIM), Rotterdam School of Management, Rotterdam School of Economics, Erasmus University Rotterdam, 2004. https://ep.eur.nl/retrieve/2750/EPS-2004-036-MKT+9058920607+APPELMAN.pdf.
Full textCostanzo, Salvatore. "Synthèse, caractérisation et spectroscopie de nanoparticules de Co et (coeur) Co / (coquille) CoO auto-organisées." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066190/document.
Full textOne of the present challenges in the field of nanomaterial chemistry is to develop strategies aimed at controlling not only the growth of metal nanoparticles (NPs), but also their long-distance organization. Another important goal is controlling the oxidation of NPs and especially the formation of complex oxides having a core (metal) @ shell (metal oxide) architecture. In this context, by revisiting micellar synthesis, a strategy based on the modification of solvent-controlled ligand-ligand interactions was established, following the modeling of the Hansen solubility, of controlling the size of cobalt NPs (3.8 nm to 9.1 nm). Dodecanoic acid NPs passives and protects from oxidation and coalescence (TEM & SAXS control). Hexagonal lattice monolayers and face-centered 3D fcc superlattices were obtained. Using two oxidation strategies combined with annealing, dry and in solution, core / shell NPs: Co (ferro) @CoO (antiferromagnetic)/ were prepared with a polycrystalline metal core cfc or monocrystalline hcp. The preliminary study of the magnetic properties (SQUID) shows that the Co / CoO interface favors a moderate ferromagnetic / antiferromagnetic exchange interaction. Raman spectroscopy, a non-invasive method, under different laser excitations allows the simultaneous analysis of the metal particle (phase control and measurement of diameters from Lamb's modes), coating agent and its interaction with the NP and the possible oxide shells (CoO/CoOH, CO3O4) as well as the dynamics of the dodecanaote chains. Infrared analysis indicates hydroxylation of the unoxidized NPs. The vibrational techniques appear well adapted to the multi-scale control of NPs assemblies and supracrystals
Yi, Jae-Young. "Microstructure and magnetic properties of Co-(CoO, CoNiO2̳, NiO) and Cox̳Ni1̳-̳x̳-CoO nanocomposite thin films /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2000. http://wwwlib.umi.com/cr/ucsd/fullcit?p3000403.
Full textBieri, Beatrice. "Kosten-Nutzen-Analyse von Ökolabels aus Sicht der Marktteilnehmer - am Beispiel Coop Naturaplan." St. Gallen, 2005. http://www.biblio.unisg.ch/org/biblio/edoc.nsf/wwwDisplayIdentifier/02605582001/$FILE/02605582001.pdf.
Full textGhadimi, Mohammad Reza. "Mikroskopischer Ursprung der unidirektionalen Anisotropie an der austauschgekoppelten CoO-Co-Grenzfläche." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=980665949.
Full textSilva, Lucas Hian da. "Desenvolvimento do nanocompósito Y-TZP/MWCNT-COOH para uso odontológico." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/23/23140/tde-21112016-171828/.
Full textThis study aim was to develop a technique for synthetize nanocomposite of Y-TZP/MWCNT-COOH (3 mol% Yttria-Stabilized Tetragonal Zirconia reinforced with COOH functionalized carbon nanotubes) with mechanical and optical properties that allow their future use as fixed dental prosthesis infrastructure and implant abutments. Thus, the following properties of the nanocomposite were investigated and compared to those measured for conventional Y-TZP (control): microstructure, flexural strength, fracture toughness, fatigue limit and optical properties. Y-TZP/MWCNT-COOH material was developed by the co-precipitation of mixed hydroxides associated with the hydrothermal/solvothermal treatment and uniaxial pressing to form blocks for CAD/CAM systems. The MWCNT-COOH powder was characterized by SEM-FEG, TEM, TGA, XRD and XRF prior to its use for the development of nanocomposite. Specimens were obtained from the Y-TZP/MWCNT-COOH material and characterized by XRD, SEM-FEG and TEM. After characterization, the material had their structural properties (density and contraction), optical, flexural strength, fracture toughness and fatigue limit compared to a conventional Y-TZP. The MWCNT-COOH material was observed to be a bundle formation of carbon nanotube covered with silica with an average length of 5.10 ± 1.34 ?m, with 90% of the measured lengths (D90) being below 6.9 ?m. It has been found to be not possible to use organic liquids on any step of the Y-TZP/MWCNT-COOH manufacturing process due to darkening of the composite, making it unfeasible to future clinical application. The hydrothermal treatment without the use of organic liquids was effective in providing the carbon nanotube coating by zirconium and yttrium oxide particles. However, this treatment led to the formation of agglomerates and particles of Y-TZP with larger than 5 ?m. A relative density of 97.4% was achieved for the Y-TZP/MWCNT-COOH composite, having a contrast ratio of 0.9929 ± 0.0012, and a color difference value from the conventional Y-TZP of 6.1 ± 3.1 (?E). The mechanical properties of Y-TZP/MWCNT-COOH, Vickers hardness (10.14 ± 1.27 GPa; p = 0.25) and fracture toughness (4.98 ± 0.30 MPa.m1/2; p = 0.39), showed no significant difference from the conventional Y-TZP (hardness: 8.87 ± 0.89; fracture toughness: 4.98 ± 0.30 MPa.m1/2). However, flexural strength (p = 0.003) and cyclic fatigue limit (CFL) showed lower values for the experimental material Y-TZP/MWCNT-COOH (flexural strength: 299.4 ± 30.5 MPa; CFL: 179.4 ± 22.5 MPa) compared to Y-TZP control (flexural strength: 623.7 ± 108.8 MPa; CFL: 439.0 ± 56.4 MPa). Based on the results presented, it could be conclude that the synthesis of a nanocomposite of Y-TZP/MWCNT-COOH with optical properties suitable for application in restorative dentistry was made possible by the described methods, however some adjustments in synthesis and processing methods for the nanocomposite creation should be taken; to avoid the sharp decrease of important mechanical properties of the material.
Groza, Georgiana irina. "Magnétisme et propriétés de transport de couches d'agrégats coeur-coquille Co/CoO." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00768030.
Full textGroza, Georgiana Irina. "Magnétisme et propriétés de transport de couches d'agrégats coeur-coquille Co/CoO." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENY020/document.
Full textThis study is focused on understanding the transport properties of granular systems core - shell with emphasis on cobalt - cobalt oxide materials. We studied the magnetic and transport behavior of our granular system ferromagnetic/ antiferromagnetic. The cobalt clusters of 4 nm are obtained by a magnetron sputtering source and vapor phase condensation. The clusters oxidized during deposition adopt a core – shell geometry with icosahedra core and a fcc structure of CoO shell. After deposition, the clusters are characterized by different methods. In situ, they are characterized in terms of the amount of matter deposited by time flight spectrometer. Ex situ, they are analyzed by the SQUID (magnetic measurement) and transport measurements. Several characteristics of our samples have been identified during the magnetic analyses. Three magnetic properties are mainly interest. The first is the exchange bias F/AF, studied on the cobalt clusters with different oxidation percentages (between 33%CoO and 95% of CoO). We found that the maximum effect is obtained for the the oxidized samples due to the increased oxide shell size. The second magnetic property is the presence of superparamagnetism modified by the exchange interaction between the core and the shell. The third is the training effect shown often by a decrease in the exchange bias and coercive field after several successive measurements. This might be attributed to the instability of the magnetic configuration obtained upon cooling under a field, but it is difficult to identify the exact origin. The transport properties of our system are underlined by the study of the resistivity, magnetoresistance and Hall resistance as a function of temperature and applied magnetic field. The variation of resistivity with temperature shows a minimum. In the same time this variation is small as a function of the temperature. This behavior is associated with the transition systems which are found between the metallic and insulator regime. The variation of the magnetoresistance with temperature is small. Its amplitude does not exceed 0.1% in all granular alloys measured. The studied system is characterized by a positive extraordinary Hall resistivity at all temperatures of measurement
Rudolph, Wolfram W., Dieter Fischer, and Gert Irmer. "jz Vibrational spectroscopic studies and DFT calculations on NaCH₃CO₂(aq) and CH₃COOH(aq)." Royal Society of Chemistry, 2014. https://tud.qucosa.de/id/qucosa%3A36074.
Full textGomes, Matheus Gamino. "Efeito hall extraordinário em multicamadas granulares de SiO2/Co/CoO com exchange bias." Universidade Federal de Santa Maria, 2012. http://repositorio.ufsm.br/handle/1/3920.
Full textGranular magnetic systems can be composed by magnetic particles or clusters with size of some nanometers. These magnetic nanoparticles present different magnetic order phases, as superparamagnetic, and they can be embedded in both, metallic or insulating matrix. These systems present several phenomena such as the giant magnetoresistance (GMR), extraordinary Hall effect (EHE), tunnel magnetoresistance (TMR) and Coulomb blockade. That phenomena use to disappear when a small termal fluctuation is high enough to reverse the magnetization of the clusters leading the lost the magnetic information in a very short time range. When it occurs, the particles are in superparamagnetic phase. In order to maintain the magnetic information at high values of temperature, or even to suppress the superparamagnetic limit, many works have tried to use an antiferromagnetic matrix, to induce the increase of the energy barrier among the two easy directions of magnetization by the exchange coupling in the grain(FM)/matrix(AFM) interfaces, with the purpose of stabilizing the particles magnetization. In this work, we have produced Co granular samples embedded in SiO2/CoO insulating/antifferomagnetic matrix through a sequential deposition by magnetron sputtering, in order to study the exchange bias of Co grains laterally surrounded by CoO.Were perfomed measurements of transmission eletronic microscopy (TEM), x-ray diffraction (XRD), measures low fields thermomagnetics (ZFC-FC), to obtain answers of the structural and magnétic charater of the samples. The Exchange Bias were investigated by extraordinary Hall effect, meauresments in differents temperature values in a cooling field (FC) of 5kOe. These non conventional measurements, are carried out with field cooling and the applied external field to perfomed the loop hysteresis both with perpendicular direction to the substrate. The effective anistropy, changes the magnitude up to three ordes of magnitude for different thicknesses of CoO in the limit T!0. On the other hand, the HEB linearily decreases, and goes to zero at a certain temperature. This temperature, is approximately, equal to that where the split of ZFC-FC curves occurs. This split is associated with the CoO blocking temperature, i.e. the ordering temperature of CoO. These results are reported from the finite size effect present in thin films. For the specific case of CoO, these effects lead to a nonzero net magnetization coming from uncompensed moments present on the surface that, in some cases, are responsible for the magnetic coupling governed by a local disorder and frustration, a spin-glass-like behavior. The extraodinary Hall effect and giant magnetoresistance were study of thin Fe-rich amorphous films and Fe-rich/Cu multilayers. Were investigated and compared the extraordinary Hall effect in these two types of samples and discussed it in terms of thickness and sample structure. The thicker films exhibited a strong in-plane magnetic anisotropy, and by decreasing film thickness both saturated Hall resistivity and Hall sensitivity increase. Electrical conductance increases and Hall resistivity decreases when the films are sandwiched with Cu.
Sistemas granulares magnéticos podem ser formados por grãos ou aglomerados magnéticos cujo tamanho é de alguns nanômetros. Estes grãos magnéticos apresentam diferentes fases de ordenamento magnético, como o superparamagnetismo, e podem estar envolvidos tanto por matrizes metálicas como matrizes isolantes. Estes sistemas possuem uma riqueza de fenômenos, como a magnetorresitência gigante (GMR), Efeito Hall Extraordinário (EHE), magnetorresistência túnel (TMR), bloqueio de coulomb entre outros. Estes fenômenos muitas vezes desaparecem quando à energia térmica for suficiente para inverter a magnetização dos grãos, levando-os a perder informação magnética num intervalo de tempo muito curto. Quando isto ocorre dizemos que os grãos estão na fase superparamagnética. Para reter a informação magnética a temperatura ambiente, ou até mesmo suprimir o superparamagnetismo, tem-se tentado o uso de uma matriz antiferromagnética (AFM) onde os grãos ficam imersos, e o acoplamento de troca na interface grão (FM)/matriz (AFM) pode induzir um aumento na barreira de energia entre as duas direções de fácil magnetização e com isso estabilizar a magnetização dos grãos. Neste trabalho foram produzidas amostras granulares de Co imersos em matriz isolante/antiferromagnética de SiO2/CoO pela deposição alternada do metal e dos isolantes por magnetron sputtering , com a finalidade de estudar a evolução do exchange bias entre os grãos de Co que estão lateralmente envolvidos por CoO. Foram realizadas medidas de Microscopia Eletrônica de Transmissão (TEM), Difração de raios-X (XRD), medidas termomagnéticas a baixos campos (ZFC-FC), para obter respostas quanto ao caráter estrutural e magnético das amostras. O Exchange bias foi investigado por efeito Hall extraordinário, medidas à diferentes temperaturas sob um campo de resfriamento (FC) de 5kOe. Estas medidas, diferente do convencional, são realizadas com o campo de resfriamento e o campo externo aplicado para realizar a curva de magnetização ambas na direção perpendicular ao substrato. A anisotropia efetiva, varia, na sua magnitude, até três ordens de grandeza para diferentes espessuras de CoO para o limite T !0. Por outro lado, o HEB decresce linearmente, até ir à zero numa dada temperatura. Esta temperatura onde extingue-se o HEB é, aproxiamdamente, a mesma onde ocorre à separação das curvas ZFC-FC. Esta separação nas curvas está associado com a temperatura de bloqueio de CoO, ou seja, temperatura de ordenamento dos grãos de CoO responsáveis pelo acoplamento direto com os grãos de Co. Estes resultados reportados são oriúndos dos efeitos de tamanho de grão, presentes em filmes muitos finos. Para o caso específico do CoO, estes efeitos levam há presença de uma magnetização diferente de zero oriúndos dos momentos não compensados presentes na superfície que, para alguns casos, são responsáveis pelo acoplamento magnético governado por uma desordem local e frustação, um compotamento do tipo spin-glass-like . Efeito Hall extraordinário e magnetorresistência gigante foram estudados em filmes finos amorfos de FINEMET e multicamdas FINEMET/Cu. Foi investigado e comparado o efetio Hall nos dois tipos de amostras, e discutido em termos da espessura e estrutura da amostra. Para os filmes mais espessos foi observado uma forte anisotropia no plano do filme, por outro lado, quando a espessura diminui ambos, a resistividade Hall satura e a sensibilidade Hall aumenta considerável. A condutividade elétrica aumenta e a resistividade Hall diminui para as multicamadas FINEMET/Cu.
Irimescu, Monika. "Social redovisning i kooperativa företag : Jämförelse mellan COOP och HSB." Thesis, University of Gävle, Department of Business Administration and Economics, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-4906.
Full textSyfte: kooperativa företag arbetar för en hållbar utveckling av sina lokalsamhällen. Samtidigt är social ekonomi bäst på socialt ansvar med en hög tillväxt inom Europa. Hållbarhetsredovisning har införts som lag för statliga företag from den 1 januari 2008. Därför undersöker jag hur olika konsumentkooperativ arbetar med den sociala redovisningsprocessen. Syftet med studien är alltså att undersöka och jämföra den sociala redovisningsprocessen hos de kooperativa företagen HSB och Coop, dvs vilka metoder, processer och mått för att mäta de sociala målen används och vilka fördelar och nackdelar har dessa.
Metod: Ett kvalitativt tillvägagångssätt (och en induktiv ansats) har använts för att utföra studien. Data har samlats in genom intervjuer som kompletterats med annan relevant information. En kvalitativ analys och jämförelse av resultaten har gjorts mellan de två kooperativen.
Resultat & slutsats: Coop och HSB har hållbarhetsredovisningar där de ekonomiska målen integreras i de sociala. HSB har en egen metod medan Coop har utgått från GRIs riktlinjer. HSB fokuserar på några frågor medan Coop har fångat de flesta frågor med social betydelse. Både den sociala redovisningsprocessen och dess resultat, det sociala bokslutet, anses vara nästan lika viktiga för båda kooperativen, lite större vikt läggs på processen hos HSB. Processen hos båda kooperativ liknar mycket varandra och är i princip samma. För mätningen av de sociala målen använder Coop både kvantitativa och kvalitativa mått medan HSB använder, än så länge, främst kvantitativa mått. För datainsamling används enkäter/webbenkäter av båda kooperativen och är den vanligaste metoden hos Coop. Orsaken till detta kan vara att via dessa kan man få både kvalitativa och kvantitativa svar. HSB använder dessutom medlemstidningen och gemensamma datakällor, medan hos Coop erhålls synpunkter genom medlems- och butiksråden och Medlemspunkten, en särskild plats i butiker där medlemmarna enkelt kan ge förslag på förbättringar eller lämna synpunkter (Coops hållbarhetsredovisning 2007, pdf, s. 38).
Bland fördelarna anges av Coop trovärdighet genom en transparent redovisning och av HSB att den underlättar samsyn och utveckling vilket bidrar till en effektiv verksamhet samt att den underlättar kommunikationen. Den sociala redovisningens nackdelar enligt HSB är att koppla indikatorer till aktiviteter medan Coop anser att icke-finansiell information kan uppfattas som svårtolkad och lättmanipulerad. Icke-finansiell information kan således vara svårt att tolka och mäta. Andra nackdelar är avsaknad av etablerade redovisningsregler (Coop) och kostnaderna ifall man skulle misslyckas (HSB).
Förslag till fortsatt forskning: Eftersom studien har begränsats på två kooperativ skulle det vara intressant att undersöka flera andra kooperativ och jämföra dem med varandra. Dessutom kunde man även undersöka de två andra områdena inom socialt ansvar som inte behandlats i studien nämligen mänskliga rättigheter och produktansvar. En annan aspekt som kunde undersökas är hur utvecklingsarbetet för social redovisning utförs inom kooperativ.
Studiens bidrag: Studien har bidragit till ny kunskap om den sociala redovisningsprocessen hos kooperativa företag, om metoder, processer och mått som används. Den kan vara värdefull för studenter eller andra som är intresserade av hur olika kooperativ arbetar med social redovisning.
Nyckelord: social redovisning, metoder, mått, sociala mål, intressenter, kooperativ, HSB, Coop.
Aim: Co-operatives work for the sustainable development of their communities. At the same time, social economy is best in social responsibility with a high growth in Europe. Sustainability accounting has been introduced as law for state companies from 1 January 2008. For these reasons, I investigate how different consumer co-operatives work with the social accounting process. Thus, the aim of the study is to examine and compare the social accounting process in the co-operatives HSB and Coop, i.e. what methods, processes and measurements to measure the social goals are used, and what are its benefits and drawbacks.
Method: A qualitative approach (and an inductive) was used for the study. Data was collected through interviews completed with other relevant information. A qualitativ analysis and comparison of the results between the two co-operatives has been done.
Result & Conclusions: Coop and HSB has sustainability reports with the economical objectives integrated into the social goals. HSB has its own method while Coop has started from GRIs guidelines. HSB focuses on a few issues whereas Coop has captured most of the issues with a social importance. Both the social accounting process and its result, the social account/report, is considered to be almost equally important for both co-operatives, but a little more weight is attached to the process by HSB. The processes by both co-operatives are very similar and, in principle, the same. For the measuring of the social targets, Coop uses both quantitative and qualitative measurements whereas HSB uses mainly quantitative measurements. For the collection of data questionnaires/web questionnaires are used by both co-operatives and are most frequently used by Coop. The reason to this could be that through these both quantitative and qualitative answers can be obtained. In addition, HSB uses the member paper and common data sources while Coop obtains viewpoints through the member- and shop council and the Memberpoint i.e. a special place in the shops, where members can give proposals for improvements or their point of view (Coops sustainability report 2007, pdf, p. 38) Among the advantages indicated by Coop is reliability through a tranparent accounting. HSB indicates that it facilitates a common view and development that contributes to an effective business and it facilitates communication. The disadvantages of social accounting according to HSB are to connect indicators to activities whereas Coop deems non-financial information possible to be seen as hard to interpret and easy to be manipulated. Non-financial information can thus be hard to interpret and measure. Other disadvantages are the lack of established accounting rules (Coop) and the costs in case of a failure (HSB).
Suggestions for future research: As the study has been limited to two co-operatives it would be interesting to investigate several other co-operatives and compare them. Besides, the two other areas of social responsibility that were not discussed in the study, i.e. human rights and product responsibility could be examined. An other aspect that could be looked into is how the work for the development of social accounting is carried out within co-operatives.
Contribution of the study: the study has contributed to new knowledge about the social accounting process in co-operatives, about methods, processes and measurements that are used. This can be valuable for students or others who are interested in how co-operatives are working with social accounting.
Key words: Social accounting, methods, measures, social objectives, stakeholders, co-operatives, HSB, Coop.
Chon, David. "Exchange bias in magnetically coupled CoO/Co bilayer measured with magnetic hysteresis loop and magnetotransport." Thesis, California State University, Long Beach, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1522621.
Full textThe temperature dependence of the exchange bias effect, a phenomenon due to the interfacial exchange coupling at the antiferromagnetic-ferromagnetic (AFM-FM) interface, is studied experimentally using CoO/Co bilayers with two different methods: magnetic hysteresis loop and magnetotransport. The exchange bias coupling in the CoO/Co gives rise to induce unidirectional anisotropy in the Co layer causing a shift in the magnetic hysteresis loops. The experimental results show that the exchange bias field decreases with increasing temperature and depends on the Co thicknesses. The exchange bias shift is inversely proportional to the ferromagnetic film thickness confirming that it is an interfacial effect. The large training effect in hysteresis loops indicates that the hysteresis loop method underestimates the unidirectional anisotropy induced by the exchange coupling. The exchange bias is also determined by measuring the anisotropic magnetoresistance (AMR). While previous measurements relied on two separate apparati for comparison, this experiment demonstrates that hysteresis loop measurements and AMR measurements can be performed in one system, the automated Physical Property Measurement System by Quantum Design. A greater magnitude in the exchange anisotropy energy is observed for measurements made with AMR compared to that of the hysteresis loop measurements.
Wiedwald, Ulf. "Interface magnetism in Co/CoO core-shell nanoparticles and their transformation to pure metallic nanoparticles." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=974954195.
Full textGomes, Matheus Gamino. "Deposição de nano-grãos de Co em uma matriz de CoO/Al2O3 por Magnetron Sputtering." Universidade Federal de Santa Maria, 2007. http://repositorio.ufsm.br/handle/1/9175.
Full textGranular magnetic systems can be composed by magnetic particles or clusters with size of some nanometers. These magnetic nanoparticles present different magnetic order phases, as superparamagnetic, and they can be embedded in both, metallic or insulating matrix. These systems present several phenomena such as the giant magnetoresistance (GMR), tunnel magnetoresistance (TMR) and Coulomb blockade. That phenomena use to disappear when a small termal fluctuation is high enough to reverse the magnetization of the clusters leading the lost the magnetic information in a very short time range. When it occurs, the nano-particles are in superparamagnetic phase. In order to maintain the magnetic information at high values of temperature, or even to suppress the superparamagnetic limit, many works have tried to use an antiferromagnetic matrix, to induce the increase of the energy barrier among the two directions of magnetization easy by the exchange coupling in the grain(FM)/matrix(AFM) interfaces, with the purpose of stabilizing the nano-particles magnetization. In this work, we have produced Co granular samples inside an Al2O3/CoO insulating/antifferomagnetic matrix through a sequential deposition by magnetron sputtering. We aim to explore the couplingmechanisms among the ferromagnetic nanoparticles and the antiferromagnetic matrix. It has been performed measurements of Impedance Spectroscopy (IS), X-ray Difraction (XRD), and magnetization at function temperature analysed by zero-field cooling/field cooling curves (ZFC-FC) at some samples in order to obtain information about the magnetic and structural properties. The measurements of IS and XRD corroborate the formation of Co clusters and the magnetization versus temperature curves to some samples do not indicate evidence of the exchange coupling among the Co clusters and the CoO antiferromagnetic matrix.
Sistemas granulares magnéticos podem ser formados por grãos ou aglomerados magnéticos cujo tamanho é de alguns nanômetros. Estes nano-grãos magnéticos apresentam diferentes fases de ordenamento magnético, como o superparamagnetismo, e podem estar envolvidos tanto por matrizes metálicas como matrizes isolantes. Estes sistemas possuem uma riqueza de fenômenos, como a magnetorresitência gigante (GMR), magnetorresistência túnel (TMR), bloqueio de coulomb entre outros. Estes fenômenos muitas vezes desaparecem quando uma flutuação térmica for suficiente para inverter a magnetização dos grãos, levando-os a perder informação magnética num intervalo de tempo muito curto. Quando isto ocorre dizemos que os nano-grãos estão na fase superparamagnética. Para reter a informação magnética a temperatura ambiente, ou até mesmo suprimir o superparamagnetismo, tem-se tentado o uso de uma matriz antiferromagnética (AFM) onde os nano-grãos ficam imersos, e o acoplamento de troca na interface grão (FM)/matriz (AFM) pode induzir um aumento na barreira de energia entre as duas direções de fácil magnetização e com isso estabilizar a magnetização dos nano-grãos. Neste trabalho foram produzidas amostras granulares de Co imersos em matriz isolante/antiferromagnética de Al2O3/CoO pela deposição alternada do metal e dos isolantes por magnetron sputtering , com a finalidade de explorar os mecanismos de acoplamento entre os nano-grãos ferromagnéticos e a matriz antiferromagnética. Foram realizadas medidas de Espectroscopia de Impedância (IS), Difração de raios-X (XRD), e magnetização em função da temperatura pelas técnicas ZFC-FC em algumas amostras, afim de se obter respostas quanto as propriedades estruturais e magnéticas. As medidas de IS e XRD, indicam a formação de nano-grãos Co e as medidas de magnetização em função da temperatura para algumas amostras, não mostraram com evidência o acoplamento de troca ( Exchange Bias ) entre os grãos de Co e a matriz antiferromagnética de CoO.
Ávila, Gutiérrez Mario Alberto. "Effet de la nanocristallinité sur les croissances homogènes et hétérogènes des supercristaux magnétique de cobalt." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS008.
Full textMetallic nanocrystals 3D self-organization (NCx) is a new generation of nanostructured materials, called supercrystals. They present a new collective property, which allows them to be involved in different technological applications. In this thesis, we propose a comparative study concerning heterogeneous and homogeneous growth in the absence or presence of a magnetic field, of cobalt nanocrystals, obtained by the micellar route (7.5 nm, σ: 11%, fcc type) and by the dismutation of an organometallic salt ([CoCl(PPh3)3]) (9 nm, σ: 10%, hc type). The former are passivated with dodecanoic acid and the latter with oleylamine. By controlling the amount of oleylamine in Co-hc NCx colloidal solution and the volume of solution deposited, we promote the growth of super crystals, relatively similar to those obtained with Co-fcc NCx. A new method of ligand exchange (from oleylamine to dodecanoic acid) is proposed, promoting Co-hc NCx whose interaction with dodecanoic acid is covalent. The deposits conducted with these NCx promote for the first time colloidal crystals of Co-hc NCx passivated with dodecanoic acid. Using a solution oxidation method, core/shell nanocrystals [Co (ferromagnetic)@ CoO (antiferromagnetic)] of uniform size were obtained with a monocrystalline metal core (hc) and an fcc shell. Preliminary studies of magnetic properties show magnetic exchange coupling at the ferromagnetic/antiferromagnetic interface
Correia, Ricardo. "Effects of climate and land management changes on conservation : of mediterranean cork oak woodlands and their bird communities." Thesis, University of East Anglia, 2014. https://ueaeprints.uea.ac.uk/50549/.
Full textCorreia, Ricardo. "Effects of climate and land management changes on conservation : of mediterranean cork oak woodlands and their bird communities." Doctoral thesis, University of East Anglia, 2014. http://hdl.handle.net/10451/16152.
Full textCork oak woodlands are a keystone habitat for Mediterranean biodiversity but are currently undergoing a global decline and widespread management changes driven by social, economic and climatic factors. I examine the effects of both climate and land management changes on cork oak woodlands and their bird communities across the western Mediterranean Basin. Future climatic scenarios indicate that up to 60% of current cork oak woodlands may become unsuitable by 2080, especially in southern areas where they will be restricted to microclimatic refugia sites. Increasing aridity, particularly in drier microclimates, will potentiate a decline of cork oak tree condition resulting in impacts across the food web that ultimately have a negative effect on breeding bird abundance and diversity, particularly for tree-dependent forest species. Farmland and shrubland birds respond mainly to habitat features modified by land management and their abundances increase in areas with open and heterogeneous ground cover. Current abandonment, intensification and overexploitation trends are likely to have negative effects on their populations but climate change can also play an important role if it provides an additional stimulus for land management changes. The unique bird assemblages of North African cork oak woodlands seem particularly vulnerable to both factors and should therefore be considered a conservation priority. Nonetheless, climate change may benefit species of Mediterranean origin and seems to have enabled the establishment of resident populations of traditionally migratory bird species in the Iberian Peninsula. This may provide new conservation opportunities for declining migratory species as long as adequate winter habitat areas are available. Adaptation strategies should aim to incorporate biodiversity-friendly management practices, promote cork oak afforestation in areas that will become climatically suitable and evaluate alternatives to provide similar economic and environmental services in the regions where cork oak woodlands are likely to disappear.
Fundação para a Ciência e a Tecnologia (FCT)
Champmartin, Delphine. "Etude structurale et dynamique en solution de molécules contenant le groupe CO ou COOH et de complexes métalliques par relaxation magnétique nucléaire." Nancy 1, 1997. http://docnum.univ-lorraine.fr/public/SCD_T_1997_0182_CHAMPMARTIN.pdf.
Full textSun, Xiaolei, Guang-Ping Hao, Xueyi Lu, Lixia Xi, Bo Liu, Wenping Si, Chuansheng Ma, et al. "High-defect hydrophilic carbon cuboids anchored with Co/CoO nanoparticles as highly efficient and ultra-stable lithium-ion battery anodes." Royal Society of Chemistry, 2016. https://tud.qucosa.de/id/qucosa%3A30234.
Full textSun, Xiaolei, Guang-Ping Hao, Xueyi Lu, Lixia Xi, Bo Liu, Wenping Si, Chuansheng Ma, et al. "High-defect hydrophilic carbon cuboids anchored with Co/CoO nanoparticles as highly efficient and ultra-stable lithium-ion battery anodes." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-221863.
Full textJeoung, Jae-Hun. "Anaerobic carbon monoxide dehydrogenase : mechanism of CO-oxidation at the [NiFe 4 S 4 OH x] cluster and nickel-processing by its ATPase CooC." kostenfrei, 2008. http://opus.ub.uni-bayreuth.de/volltexte/2008/495/.
Full textSpence, Janet G. "The relationship between cooperative education student work values and work site manager's referent power." Connect to this title online, 2003. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1047503508.
Full textTitle from first page of PDF file. Document formatted into pages; contains xi, 127 p.: ill. Includes abstract and vita. Advisor: David S. Stein, School of Physical Activity and Educational Services. Includes bibliographical references (p. 120-127).
Courty, Colette. "Détermination par diffraction X des contraintes résiduelles dans les oxydes formés sur les métaux à haute température cas des systèmes Ni/NiO et Co/CoO /." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37612798j.
Full textShuwaikan, Mohammed Salem. "Investigation of the uptake, co-localisation, biological effects, and toxicity mechanism(s) of carboxyl-modified polystyrene nanoparticles (COO-PS-NPs) onto human bronchial epithelial (BEAS-2B) cells." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/6155/.
Full textLagerqvist, Ulrika. "Solution-Chemical Synthesis of Cobalt and Iron:Zinc Oxide Nanocomposite Films." Doctoral thesis, Uppsala universitet, Oorganisk kemi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-280619.
Full textGekas, Paulo Demetre. "Correlações entre desafinado e moon dreams: uma análise dos processos lineares e harmônicos." Universidade do Estado de Santa Catarina, 2005. http://tede.udesc.br/handle/handle/2183.
Full textCoordenação de Aperfeiçoamento de Pessoal de Nível Superior
It is noticed, in literature, and about Brazilian popular music the affirmative comments about the similarity existent between Bossa Nova and Cool Jazz that may be a result from the possible adoption of Cool Jazz elements by Bossa Nova composers. This research has its origin in the need to locate, via musical analysis, co-relationships between representative works from the Cool Jazz and Bossa Nova. Two arrangements works, one of each kind, were selected, nominated by that literature, as representative: Desafinado from the composer Antônio Carlos Jobim in partnership with Newton Mendonça with arrangements by Jobim and Moom Dreams by Chummy MacGregor in partnership with Johnny Mercer with arrangements by Gil Evans. For the selection of those arrangements three aspects were taken into consideration: representation of the works, the originality and the notoriety of the arrangement. From Arnold Schoenberg and Almir Chediak s perspective, aspects concerning the melodic stratum were collected and related, via the analysis of the linear and harmonic processes, aspects concerning the melodic stratum such as basic motive, melodic variation procedures and motivic traces. And the harmonic processes including the polyphonic and homophonic resources, cadences, modal loan chords, superstructure chords, interval relationship between bass line and melody, modulations, auxiliary notes. As a result of the hereto made analysis it was noticed the existence of co-relationships between those works regarding the motivic traces, motivic variation procedures, cadences, superstructure chords, interval relationship between bass line and melody, modal loan chords and auxiliary notes. The survey of those aspects allowed, in a restrict way to those arrangements, to profoundly study and confirm some of the affirmative comments existent in literature concerning the common characteristics to those musical styles
Na literatura sobre música popular brasileira verifica-se a reiterada afirmação a respeito de uma possível assimilação de elementos do Cool Jazz por compositores da Bossa Nova. Esta pesquisatem sua origem na necessidade de localizar, por meio da análise musical, correlações entre obras representativas dos estilos Cool Jazz e Bossa Nova. Foram selecionados dois arranjos de obras indicadas pela literatura como representativas, sendo um de cada estilo: Desafinado do compositor Antônio Carlos Jobim em parceria com Newton Mendonça, arranjada por Jobim e Moon Dreams, de Chummy MacGregor em parceria com Johnny Mercer, arranjada por Gil Evans. Para a escolha desses arranjos foram levados em consideração três aspectos: a representatividade das obras, a originalidade e notoriedade do arranjo. Dentro da perspectiva de Arnold Schoenberg e de Almir Chediak foram levantados e relacionados, através da análise de processos lineares e harmônicos, aspectos concernentes ao estrato melódico tais como: motivo básico, procedimentos de variação melódica e traços motívicos e aos processos harmônicos, entre eles: recursos polifônicos e homofônicos, cadências, acordes de empréstimo modal, acordes de superestrutura, relação intervalar entre linha do baixo e melodia, modulações e notas auxiliares. Como resultado das análises aqui realizadas observou-se a existência de correlações entre as obras no que diz respeito aos traços motívicos, procedimentos de variação motívica, cadências, acordes de superestrutura, relação intervalar entre linha do baixo e melodia, acordes de empréstimo modal e notas auxiliares.
Neubeck, Wolfgang. "Etude des propriétés magnétiques et électroniques des oxydes de métaux de transition MnO, CoO, NiO et CuO par diffraction magnétique de rayons X." Université Joseph Fourier (Grenoble), 2000. http://www.theses.fr/2000GRE10216.
Full textJian, Chung-Chin, and 簡崇欽. "Magnetic Tunneling Effect in Co/CoO/Fe3O4 and Fe3O4/AlOx/Co Junctions." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/79838508059773261672.
Full text國立臺灣大學
物理學研究所
92
Abstract Magnetic trilayer junctions(MTJs) based on half metallic oxides have attracted much attention because of their potential in memory and logic device applications. Among half metallic materials, the magnetite(Fe3O4) is the most promising candidate due to its high ferrimagnetic Curie temperature(~856K). And an enhanced TMR effect has been expected for this sort of MTJ. However, up to now, the MR effect of MTJ with Fe3O4 as an electrode has been found to be negligibly small. Several causes have been speculated to explain the reduction. For examples, the spin flip processes on the interface would have a deleterious effect on the MR. A less-than ideal insulating barrier containing impurities and defects would also lead to spin scattering. In order to explore the major origins of reduction in MR, we have systematically investigated the TMR of MTJs prepared under various conditions. Our MTJs consist of Fe3O4 and Co as the electrodes sandwitched with cobalt oxide and AlOx thin layers as the tunneling barriers for comparison. The choice of Fe3O4 and Co as the electrodes is due to a large difference of coercivities from these two magnetic layers. Besides, a thin oxide layer can be directly obtained from oxidation of the metal layer right after deposition of the metal, where metals are Co and Al, respectively. We have adopted different oxidation time to acquire tunneling barrier of various thickness. Thus, the impact of tunneling barrier on TMR can be evaluated. Furthermore, since the polarization of Fe3O4 has been predicted to be negative, the inverse MR will be also studied. In Our MTJs, the resistance of electrode Fe3O4 is too large compared to the junction''s, then it would cause nonuniform current distribution over the junction area. Thus, negative resistance will be obtained by using four-probe measurement. We try to reduce the junction area from mm2-size to um2-size to pursuit a uniform coverage of the barrier on the electrode in MTJs. For this purpose, we learn to use E-beam lithography technique to make um2-size magnetic films. We also fabricate hundreds of nm size Co dot arrays to investigate its properties.
He, Yiping. "Transcription activation by CooA - a CO sensing factor from Rhodospirillum rubrum." 1999. http://catalog.hathitrust.org/api/volumes/oclc/45383000.html.
Full textLucena, Filipa Maria Salgado de Sousa. "How to Launch Cork & CO in Australian market : defining strategy." Master's thesis, 2015. http://hdl.handle.net/10400.14/17969.
Full textCORK&CO, uma microempresa portuguesa no setor de moda e design em cortiça pretende expandir os seus negócios para a Austrália. Para analisar este processo de internacionalização e aconselhar a melhor estratégia a seguir, foram desenvolvidos três diferentes cenários: para um modelo típico de investimento (através da instalação de uma loja própria), para um modelo de base contratual (através da criação de um franchising) e para um modelo tradicional de exportação (venda direta a revendedores). A CORK&CO não tem fundos próprios que lhe permitam suportar o investimento que alguns desses cenários implicam. Por isso, foram estudadas soluções de financiamento bancário e da União Europeia para determinar quais as alternativas que poderiam ser seguidas. O elevado nível de investimento, a incerteza do mercado e a impossibilidade de recorrer a fundos europeus tornam o primeiro cenário fortemente desaconselhável, deixando a empresa com apenas duas possibilidades de expansão: através de um franchising ou através da exportação direta.
You-Jing, Chou. "Synthesis,microstructure and magnetic properties of Co-CoO nanocrystalline thin films." 2005. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2607200503484200.
Full text陳俊明. "Magnetic properties of Co/CoO/Ir(111) grown on Ir(111)." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/60182782145674187312.
Full text張新政. "Magnetic properties of ultrathin CoO/Co bilayers grown on semiconductor substrates." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/37361966651377454083.
Full textChou, You-Jing, and 周佑靜. "Synthesis、microstructure and magnetic properties of Co-CoO nanocrystalline thin films." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/52697555815408623507.
Full text國立臺灣大學
材料科學與工程學研究所
93
Co-CoO nanocrystalline films are synthesized by RF reactive sputtering method. The films are deposited on Si (100) substrate. There are two parts in this work: first, we deposit pure Co films with different grain sizes by controlling the deposition rate. In addition, we also deposit Co on Si (100) with different substrate temperature. Second, we adjust the appropriate input oxygen/argon pressure, and deposit Co-CoO nano-crystallline films. With different oxygen/argon ratio and different deposition rates, we can control grain size in certain range. The addition of CoO enhances coercivity of Co greatly, and it is due to the exchange coupling between Co and CoO. We also investigate the correlation between exchange bias and the microstructure of the thin films. In Co films, the results show that the increase of coercivity is related to grain size. The films deposited at high substrate temperature have the larger grains and show the same trend. However, the remanence decreases as the substrate temperature increases. Moreover, the structure of thin films is transformed from HCP to FCC as the substrate temperature is raised up to 300 ℃. In Co-CoO films, we observe a nanostructure-dependency of coercivity. The addition of oxygen pressure enhances coercivity greatly. Exchange bias stems from the coexistence of CoO and Co. The best exchange bias in our films occurs when the O2/Ar ratio= 2% and the deposition rate was 3.4 nm/min, which is related to an effective nanostructure of Co-CoO.
Wang, Yu-Chieh, and 王煜傑. "-ray linear dichroism for Sr3Cr2O8、CoO、Co(NO3)2 and SrCuO2." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/2g8gx2.
Full text國立交通大學
物理研究所
104
We utilized synchrotron radiation linear polarized light to explore Sr3Cr2O8, CoO, Co (NO3)2 and SrCuO2 for its orbital ordering and electronic structure. In this thesis, Sr3Cr2O8 and CoO projects are supervised by Dr. Chun-fu Chang of Max Planck Institute, Dresden, Germany. For Sr3Cr2O8, we used linear polarized x-ray to measure the single-crystal sample for Cr L-edge absorption spectra to explore the chromium electronic structure and spin dimers formation, and Jahn - Teller Distortion. Along with the multiplet theory, we find the ground state wave functions, orbital ordering, as well as the electronic structure for Sr3Cr2O8. We also study cobalt oxide and cobalt nitrate using linear polarized light of Co L-edge x-ray absorption spectroscopy and deploy theoretical calculations in order to analyze the spectra. In the case of cobalt oxide, we use extendable substrate MICA in order to investigate the effect of the strain influence on the thin films. However, from the results, it seems that the mechanism for CoO growth on MICA is only related to Van deel war force. In the Co(NO3)2, cobalt ions have two different sites, which is divided by the way they are distorted. Assisted by the theoretical calculations, we find out that even the cobalt ions are in different local structure, they still show a total spin of 3 / 2 as the purely high-spin state. In addition, we also focus on SrCuO2. We want to investigate how the thickness of SrCuO2 influences the crystal field. It is an essential element for shaping superconductivity. Our result indicates that if the thickness is thinner than 10 unit cells, it grows in chain-like structure; while above 10 unit cells, it become plane-like structure leading to superconductivity with appropriate doping.
Wu, Yan-Ru, and 吳彥儒. "Ab-initio Studies of the Magnetic Properties of CoO/Co Interfaces." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/00070133141446754561.
Full text國立中興大學
精密工程學系所
104
The Density functiomal theory derived from first-principles was adopted to simulate the interface structure of CoO/Co and determine the most stable one subsequently. In addition, its magnetic properoty and the probability of phase transformation can be calculated when either the tensile or compression was exerted on the bulk CoO/Co. The results show that the most stable structure at the CoO/Co interface was rs-CoO(111)/fcc-Co(111) at which the magnetic moment was varying from 1.58 uB to 1.8 uB and from 1.8 uB to 1.92 uB in the Co and CoO layers, respectively. In the study about phase transformation, the magnetic moments was lifted from 2.22 uB to 2.36 uB and from 2.17 uB to 2.61 uB in the AFM CoO and FM Co bulks, respectively as the bulk volume was increased from 103.24 Å3 to 123.6 Å3 and from 104.01 Å3 to 126.87 Å3. No phase transformation was observed within 3% of lattice deformation resulead from the tensile and compression.
Huang, Cheng-Kai, and 黃鉦凱. "Size effects on Exchange bias Coupling in patterned Co/CoO Bilayers." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/05397772158689335747.
Full text國立交通大學
電子物理系所
103
The main purpose of this work is to investigate the size dependence of exchange bias coupling in patterned Co/CoO bilayers by using magneto-transport measurement. For patterned Co planar wires of high aspect ratio, because of shape induced anisotropy, these wires should tend towards a single domain states and its magnetoresistance curve might be symmetrical to the magnetic field axis. Meanwhile, for which there is a CoO layer beneath it, these wires seems to be multi-domain state, and exhibited magnetoresistance curve displaced along the magnetic field axis, which is called exchange bias coupling effect. Samples were fabricated by lithography technique and DC Sputtering with sample length being kept at 30 μm and its width varying from 0.2μm to 1μm. The sample thickness is Co(28nm)/CoO(2nm), and single Co layer(30nm) also be fabricated to be contrast. For single Co layer, wires narrower than 1μm tend towards a single domain states, and in line with anisotropy magnetoresistance as we expected. The switching field of wires can be fitted with a single hyperbolic function, and it decrease as width rise. In LMR(Longitudinal magnetoresistance) curve, only 10 Oe shift along the magnetic field axis, so there is only little contribution to exchange bias coupling of edge oxidation. At 100K, we find that Co/CoO bilayer wires have much more significant exchange bias coupling effect than single Co layer, and we also find the reduction of exchange bias coupling field as widths decrease. Except for magnetoresistance curve shift to negative field, a few samples exhibited magnetoresistance curve displaced positively along the magnetic field axis, which means that Co/CoO interface might have different magnetic moment arrangement in the same procedure. Besides, we also observed coercivity enhancement and training effect, but they are insensitive with the aspect ratio.
Wang, Chi-chun, and 王基駿. "The Structures and Magnetic Properties of Ta/Co/CoO/SiO2 Thin Films." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/6zk2jr.
Full text國立中興大學
材料科學與工程學系所
101
The composite films of Ta/Co/CoO on Si substrate was prepared by dual ion-beam deposition technique. The structural and magnetic properties of the composite films were studied by X-ray diffraction(XRD),transmission electron microscopy(TEM), Vibrating sample magnetometer(VSM),respectively. XRD results have shown that Ta layer consisted of B.C.C. with a＝3.31 A, Co layer consisted of H.C.P. with a＝2.51A,c＝4.05A, and CoO layer consisted of F.C.C. with a＝4.27A.TEM results have shown that the grain size of polycrystalline composite films range from 5 to16nm. Magnetic properties at room temperature (298K) and magnetic field along the parallel and perpendicular to the film surface have been measured,and the results showed that the easy axis of specimen is in-plane.In addition, Ta/Co/CoO film exhibits no exchange bias field (Hc～6.8 Oe) at room temperature, but at 180K,the temperature below the antiferromagnetic Neel temperature (Co～290K),a slightly increased exchange bias field (Hex~ 3.6 Oe) was observed.
Chuang, Po-ching, and 莊柏青. "Studies of interface and magnetic properties of CoO/Co grown on Ge(111)." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/31525126566069278849.
Full text國立中正大學
物理所
94
The main purpose of this research is to systematically study the interface and magnetic properties of ultrathin CoO/Co/Ge(111) films in the ultra high vacuum (UHV), and this topic has been attacked using surface magneto-optic Kerr effect (SMOKE) technique for magnetic measurement, Auger electron spectroscopy (AES) for compositional analysis and Reflection high energy electron diffraction(RHEED) for structure analysis. From AES and RHEED analysis. The CoO structure of ultrathin CoO/Co/Ge(111) film is short range ordering FCC phase. In 10 ML CoO/x ML Co/Ge(111) series films, with increasing Co thickness, exchange bias field increases from 0 Oe for x=10 to 583 Oe for x=20 and decreases from 583 Oe for x=20 to 312 Oe for x=40. On the other hand, in y ML CoO/20 ML Co/Ge(111) series films, with increasing Co thickness, exchange bias field increases from 0 Oe for y=0 to 583 Oe for y=10 and decreases from 583 Oe for y=10 to 151 Oe for y=35.
許志榮. "Exchange-bias phase diagram of CoO/Co/Si(111) and magnetic properties of Co/Ag-Si √3×√3/Si(111)." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/14394464097149320427.
Full text國立臺灣師範大學
物理學系
99
In this thesis, we focus on the physical properties of CoO/Co/Si(111) and Co/Ag-Si √3 × √3/Si(111) systems. For CoO/Co/Si(111) with CoO thickness between 5 and 15 monolayers (ML), a phase diagram of the exchange bias has been established by way of comparing the results of zero-field cooling and field cooling. For CoO thinner than 10 ML, enhanced coercivity is observed because of the existence of nano-sized CoO particles at the interface. For CoO thicker than 15 ML, non-zero exchange field is observed because the magnetic anisotropy is large enough. For a Co/Ag-Si √3 × √3/Si(111) system, Co overlayer has been deposited on the top of Ag-Si √3 × √3/Si(111) surface alloy. For Co thinner than 4.38 ML, no Kerr signal is detected in the longitudinal configuration. The easy axis of magnetization for Co/Ag-Si √3 × √3/Si(111) is in the surface plane. By extrapolating the data for Kerr signal versus the Co thickness, the zero intercept shows no magnetic dead layer. This shows that the Ag-Si √3 × √3/Si(111) surface alloy is efficient for preventing the silicide formation between the Co layer and the silicon substrate. From the cryogenic treatments of the specimens, the Curie temperature of 3.65 ML Co/Ag-Si √3 × √3/Si(111) is between 275 and 300 K. while that of 3.51 ML Co/Ag-Si √3 × √3/Si(111) is below 150 K. In addition, my designs and efforts on the movement and reestablishment of the ultrahigh vacuum system have been discussed.
Clark, Robert W. "Investigating the roles of the axial ligands and heme coordination changes in the CO sensor, CooA." 2005. http://catalog.hathitrust.org/api/volumes/oclc/65197707.html.
Full textHsueh-Cheng, Feng, and 馮學正. "Studies of Magnetic Properties of Ultrathin CoO/Co Film Grown on Ge(100) Surface." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/89380414750677865396.
Full textLiang, Pen-Ken, and 梁本根. "The structures and magnetic characterization of ion-beam sputtered CoO/Co/SiO2 thin films." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/55245109993826990161.
Full text國立中興大學
材料科學與工程學系所
103
In this study, the anti-ferromagnetic layer (CoO) and the ferromagnetism layer (Co) was prepared for dual ion beam sputtering (DIBS) to discuss the influence of microstructural and magnetometry properties. Step1. sputtering (Co) layer on sio2 substrate by using Kaufman ion source, Step2. sputtering (CoO) layer on (Co) layer. The (CoO) and (Co) bilayers consisted of a h.c.p. structure (Co, a=2.5Å，c=3.9Å) and a (15% O2/Ar) f.c.c. (rock-salt) structure (CoO, a=4.3Å).The TEM cross section shown the (Co) layer about 60nm and the (CoO) layer about 55nm, the interface between (CoO) and (Co) bilayers was very neat not diffuse and mixed.The CoO/Co grain size about 10~40nm from bright field and dark field. Measurement CoO/Co bilayers at room temperature, the Hc about 252Oe, the Hex shifting was not obvious, the cause of the room temperature higher than anti-ferromagnetic layer (CoO) Neel temperature (291K), the anti-ferromagnetic layer was paramagnetism, the CoO/Co bilayers was no exchange coupling effect. The CoO/Co/SiO2 ion bombardment depth profiling time at 1, 7, 15 minutes, each layer composition percentage were different,there are variations in each layer interface,but on other area composition were uniformity, no diffuse and no mixed each other.
Ghadimi, Mohammad Reza [Verfasser]. "Mikroskopischer Ursprung der unidirektionalen Anisotropie an der austauschgekoppelten CoO-Co-Grenzfläche / vorgelegt von Mohammad Reza Ghadimi." 2006. http://d-nb.info/980665949/34.
Full textMichael and 張惟祐. "Investigations of magnetic properties for oxygen adsorption and ultra-thin CoO films on Co/Si(111)." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/26924735139494980922.
Full text國立臺灣師範大學
物理學系
96
Abstract The purpose of this research is to study effect of oxygen exposure and ultrathin antiferromagnetic CoO films on the magnetic properties of ultrathin Co/Si(111)-7×7 surface. All experiments were in-situ performed in an ultrahigh vacuum (UHV) chamber with a base pressure of 2.5×10-10 torr, which was equipped with Auger electron spectroscopy (AES) for surface composition analysis, low-energy electron diffraction (LEED) and reflection high energy electron diffraction (RHEED) for surface structure analysis, and surface magneto-optic Kerr effect (SMOKE) for magnetic properties measurement. For Si (111)-7×7 surface and CoSi2 interface, it is found that oxygen is weakly adsorbed. As the thickness of Co films increases to above 5 monolayers (ML), pure cobalt islands start to accumulate on the surface and the amount of oxygen on the surface increases with increasing the oxygen exposure time. The adsorbed oxygen influences the electronic density of states of Co and leads to the decrease of saturated and remanent magnetization and poor squareness of demagnetization. The trend of coercivity with oxygen exposure is mainly governed by two competed factors: one is the reduction in the effective ferromagnetic Co films, resulting in the decrease of the coercivity; another is the action of oxygen as pinning sites to impede the magnetization reversal, leading to the enhancement of the coercivity. On other hand, the method to fabricate the antiferromagnetic CoO film is the evaporation of Co in oxygen atmosphere. As ultrathin CoO film is grown on 11 ML Co/Si(111) films, the direction of easy axis is transformed from in-plane to canted-out-of-plane. Interestingly, both longitudinal and perpendicular exchange bias phenomena are observed for 15 ML CoO/ 11 ML Co/Si(111) films measured at T = 150 K after cooling in a field H = 700 Oe from T = 300 K, and the maximum perpendicular exchange bias field of 924 Oe and the blocking temperature of 164 K are attained for 15 ML CoO, while the maximum longitudinal exchange bias field of 258 Oe and the blocking temperature of 200 K are obtained for 20 ML CoO.
Wiedwald, Ulf [Verfasser]. "Interface magnetism in Co/CoO core-shell nanoparticles and their transformation to pure metallic nanoparticles / von Ulf Wiedwald." 2004. http://d-nb.info/974954195/34.
Full textLan, Tien-Chi, and 藍天琪. "The microstructural and magnetic characterization in NiFe/CoO/Co trilayers and ion-beam bombarded NiFe/Fe-oxide bilayers." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/9twyks.
Full text國立中興大學
材料科學與工程學系所
101
Exchange bias (EB) is the term used to describe the unidirectional anisotropy found in a ferromagnet (FM) exchanged-coupled to an antiferromagnet (AFM). In this research, a dual ion-beam deposition technique was used to prepare the NiFe/CoO/Co trilayers with different CoO thicknesss and NiFe/Fe-oxide bilayers for ion-beam bombardment. Results have shown that the trilayer consisted of f.c.c. NiFe, roak-salt CoO, and h.c.p. Co structures. At room temperature, the NiFe/CoO/Co trilayers exhibited soft magnetic properties with coercivity close to those of reference single NiFe and Co layer, However, a step with enhanced Hc was observed in a NiFe/CoO(5 nm)/Co trilayer. The exchange bias coupling interaction between NiFe/CoO and CoO/Co was set in when field-cooling the trilayers below the Neel temperature of CoO down to 10 K. A largest exchange bias field (Hex ~ -143 Oe) resulting from competition between top and bottom FM/AFM interfaces was found in a NiFe/CoO(12 nm)/Co trilayer. In the ZFC/FC results, the NiFe/CoO/Co trilayers exhibited spin-glass-like behavior, while the different block temperature and irreversible temperature were caused by ferromagnetic/ antiferromagnetic coupling with different cobalt oxide thickness. Moreover, the preliminary PNR data were consistent with the hysteresis loop. The exchange coupling effects in NiFe/Fe-oxide bilayers consisted of f.c.c. NiFe and corundum h.c.p. α-Fe2O3 structures, there were no intermixing at ferromagnetic/ antiferromagnetic surface as characterized by Electron Spectroscopy for Chemical Analysis (ESCA). Without the exchange bias at 298 K, and after 70 V Ar ion bombarded observed decrease in Hc after field cooling (FC) to 160 K is mainly attributed to a reduced effective magnetic anisotropy. The hysteresis loops were measured parallel to the film surface after being field cooled from room temperature down to 10 K at 20 kOe. The enhanced coercivity (Hc ~ 204 Oe) for not bombarded NiFe/Fe-oxide bilayer and a maximum exchange bias (Hex ~ -261 Oe) was discovered at after 70 V bombarded. The results of ZFC/FC were discovered a largest block temperature (TB ~ 110 K) with 70 V bombarded, whereas the largest irreversible temperature (Tirr.) about 250 K observed at the NiFe/Fe-oxide bilayer at sample of not bombarded.
Reynolds, Mark Fredric. "Studies on the mechanisms of activation of no-sensing soluble guanylyl cyclase from bovine lung and co-sensing CooA from Rhodospirillum rubrum." 1998. http://catalog.hathitrust.org/api/volumes/oclc/42897256.html.
Full textJeoung, Jae-Hun [Verfasser]. "Anaerobic carbon monoxide dehydrogenase : mechanism of CO-oxidation at the [NiFe4S4OHx] cluster and nickel-processing by its ATPase CooC / vorgelegt von Jae-Hun Jeoung." 2008. http://d-nb.info/99196344X/34.
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