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1
Oates, Colin John. "Magnetic studies of cobalt based granular thin films." Thesis, University of St Andrews, 2002. http://hdl.handle.net/10023/12928.
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The magnetic recording media used for hard disks in laptops and PC's is constantly being improved, leading to rapid increases in data rate and storage density. However, by the year 2010, it is predicted that the superparamagnetic limit will be reached, which is potentially insufficient for data storage. At the beginning of this century, CoCr -based alloys are used in longitudinal media since cobalt has a high magnetocrystalline anisotropy. In this thesis, the static and dynamic properties of longitudinal recording thin films were investigated in order to explain and correlate their magnetic characteristics to their recording properties. The samples in question were test samples and some were in commercial use. Magnetic techniques such as high field ferromagnetic resonance and torque magnetometry were used to determine accurately the crystalline anisotropy field. High field ferromagnetic resonance is an ideal tool to determine the crystalline anisotropy, magnetisation, Lande g-factor and the gyromagnetic damping factor. In contrast to previous work, there are no FMR simulations and so all the relevant parameters were determined directly from measurement. Ideally, there should be no exchange interactions between the neighbouring cobalt grains; however, interactions between the grains within the CoCr-alloy recording layer exist. Previous work on the measurements of interactions in recording media involves measuring the sample's magnetisation. In this thesis, an alternative novel method involves torque magnetometry. Another technique that was used in this thesis is small angle neutron scattering, which aims to determine the size of the magnetic grains and compare that with the physical size determined from TEM, by Seagate. There is an extended section on CoxAg1-x granular thin films, which involves determining the sample's g-factor, effective anisotropy, grain size, exchange constant and comparing the FMR lineshapes at 9.5 and 92GHz.
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Espinosa, Jorge D. "De-wetting of cobalt thin films on sapphire." Morgantown, W. Va. : [West Virginia University Libraries], 2007. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5314.
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Thesis (Ph. D.)--West Virginia University, 2007.Title from document title page. Document formatted into pages; contains ix, 106 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 102-105).
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Joyce, David Edward. "The structure of cobalt based multilayer thin films." Thesis, University of Salford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300769.
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Jackson, Matthew. "Microwave spectroscopic studies of cobalt chromium thin films." Thesis, University of York, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387554.
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Spillane, Liam Jonathan. "Nanoanalytical electron microscopy of cobalt ferrite thin films." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/6447.
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Electron energy‐loss spectroscopy (EELS) is a powerful method for providing detailed information on the bonding, chemical structure and electronic structure of materials. In this work, EELS has been used to correlate variations in magnetic properties of cobalt ferrite films with film thickness and post‐processing conditions. Magnetometry performed on as‐deposited and oxygen post‐annealed films has shown saturation magnetization (Ms) to be strongly affected by post processing. This has been attributed to an enhancement in superexchange by reoxidation and cation ordering processes during post‐anneal. To date this has not been confirmed using nanoanalytical techniques. This work addresses this issue. In particular, it is of interest to determine local changes in the degree of inversion of the ferrite spinel in order to link local chemical changes to bulk magnetic properties. Two sample preparation techniques were used to produce electron transparent sections – conventional ion beam milling and focussed ion beam (FIB) milling using a dual beam system. The suitability of each technique is discussed in terms of, sample damage, thickness, reproducibility and reliability. Aberration corrected HRTEM was used to investigate the microstructure of the thin films. Lattice strain and defect strain were quantified at increasing distance from the substrate/interface in as‐deposited and oxygen post‐annealed cobalt ferrite films and structural defects responsible for misfit accommodation were characterised. Local variation in cation valence and coordination cobalt in an oxygen post‐annealed film was investigated by monochromated EELS of the iron and cobalt L2,3‐edges in the electron energy‐loss spectrum. A method to determine the spinel degree of inversion (λ) by multiple linear least squares fitting was developed using data acquired from reference materials. A commercially available full multiple scattering code (FEFF 8.2) was used to aid interpretation of reference spectra and the fitting technique used to determine λ was applied to the cobalt ferrite thin film in order to identify variations in λ.
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Ogrin, Feoder. "Ferromagnetic resonance studies of cobalt films and cobalt based multilayers produced by MOCVD." Thesis, Keele University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362165.
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Wiedmann, Michael Helmut. "Magnetic and structural properties of ultra-thin cobalt films." Diss., The University of Arizona, 1994. http://hdl.handle.net/10150/186876.
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In situ polar Kerr effect measurements have been used to study the magnetic anisotropy of Au(111)/Co/X, Pd(111)/Co/X, Cu(111)/Co/X, and Pd(100)/Co/X sandwiches, where X is the nonmagnetic metal Ag, Au, Cu, Ir, and Pd or the insulator MgO. The films were grown by molecular beam epitaxy (MBE). For the metals, we found that the magnitude of the Co/X perpendicular interface anisotropy is strongly peaked at ∼1 atomic layer (1.5-2.5 Å) coverage. To investigate structural influences on the anisotropy, we have used reflection high energy diffraction (RHEED) and low energy electron diffraction (LEED) to measure changes resulting from overlayer coverage. Analysis of digitized RHEED images captured every ∼1 Å during metal overlayer coverage shows no abrupt change of the in-plane lattice constant. We have also investigated the out-of-plane lattice spacing as a function of nonmagnetic metal coverage by measuring LEED I-V curves along the (0,0) rod. In the case of Cu, where the LEED behavior is nearly kinematic, we see no evidence of any abrupt structural changes at ∼1 atomic layer coverage. These results suggest the observed peak in magnetic anisotropy is not structural in origin. The influence of an insulating overlayer, MgO, on the perpendicular magnetic properties was also investigated.
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Ramos, Ana V. "Epitaxial Cobalt-Ferrite Thin Films for Room Temperature Spin Filtering." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2008. http://tel.archives-ouvertes.fr/tel-00394398.
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Le filtrage de spin est un phénomène physique qui permet de générer des courants d'électrons polarisés en spin grâce au transport sélectif à travers une barrière tunnel magnétique. Dans cette thèse, nous présentons une étude du matériau ferrite de cobalt (CoFe2O4), dont le caractère isolant et la température de Curie élevée en font un très bon candidat pour le filtrage de spin à température ambiante. L'élaboration des couches minces de CoFe2O4 a été réalisée par épitaxie par jets moléculaires assistée par plasma d'oxygène. Les propriétés structurales, chimiques et magnétiques ont été étudiées par plusieurs méthodes de caractérisation in situ et ex situ. Des jonctions tunnel à base de CoFe2O4 ont été préparées pour des mesures de transport tunnel polarisé en spin, soit par la méthode de Meservey-Tedrow, soit par des mesures de magnétorésistance tunnel (TMR). Dans ce dernier cas, nous avons porté une attention particulière au retournement magnétique de la barrière tunnel de CoFe2O4 et de la contre électrode magnétique (Co ou Fe3O4), une étape cruciale avant toute mesure de TMR. Dans les deux cas, les mesures de transport tunnel polarisé en spin ont révélé des polarisations significatives du courant tunnel à basse température, et à température ambiante pour les mesures de TMR. Par ailleurs, nous avons trouvé une dépendance unique entre la TMR et la tension appliquée qui reproduit celle prédite théoriquement pour les barrières tunnel magnétiques. Nous démontrons ainsi que les barrières tunnel de CoFe2O4 constituent un système modèle pour étudier le filtrage de spin dans une large gamme de températures.
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Yang, Jing. "Chemical Vapor Deposition of Cobalt-based Thin Films for Microelectronics." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:11299.
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In microelectronics, the device size continues to shrink to improve the performance and functionality, which sets technical challenges for the integrated circuit (IC) fabrication. Novel materials and processing techniques are developed to maintain excellent device performances and structural reliability. Cobalt-based thin films possess numerous applications in microelectronics with the potential to enhance the device performance and reliability. This thesis explores the fabrication, characterization and application of cobalt-based thin films for microelectronics. Chemical vapor deposition (CVD) technique has been applied for depositing cobalt-based thin films, because CVD can produce high quality thin films with excellent conformality in complex 3D architectures required for future microelectronics.Engineering and Applied Sciences
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Cooke, Michael D. "Magnetostrictive properties of polycrystalline iron cobalt films." Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340249.
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Tuan, Allan C. "Epitaxial growth and characterization of cobalt-doped zinc oxide and cobalt-doped titanium dioxide for spintronic applications /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/9878.
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Wei, Guang. "Lithium cobalt oxide thin films : preparation and characterization for electrochromic applications /." Thesis, Connect to Dissertations & Theses @ Tufts University, 1991.
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Thesis (Ph.D.)--Tufts University, 1991.Submitted to the Dept. of Electrical Engineering (Electro-Optics Option). Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Van, Leeuwen Robert Alan. "Structural and magnetic properties of cobalt/palladium superlattices, ultra-thin cobalt films and manganese antimony alloys." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186431.
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Structural, magnetic, and magneto-optical properties of Co/Pd and Co/Pd/Cu superlattices, ultra-thin Co films and MnSb alloys have been studied. The superlattices and Co films were grown by molecular beam epitaxy (MBE) while the MnSb alloy films were made by sputtering techniques. Several x-ray diffraction techniques were used to analyze the physical structure of the superlattices and alloys. Magnetometry techniques were used to determine some of the room temperature and temperature dependent magnetic properties of the films. In situ and ex situ measurements of the magneto-optical properties of the ultra-thin Co films and alloys also were made.
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Kabre, Tushar Shriram. "Co3O4 Thin Films: Sol-Gel Synthesis, Electrocatalytic Properties & Photoelectrochemistry." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1316552072.
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Amiri-Hezaveh, A. "Photelectron spectroscopy of ultra-thin epitaxial f.c.c. magnetic films of iron and cobalt." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233668.
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Subba, Rao Karavadi. "Microstructure and Texture of Yttrium-Nickel-Borocarbide and Samarium-Cobalt Thin Films." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2006. http://nbn-resolving.de/urn:nbn:de:swb:14-1153317232040-33715.
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The goal of this thesis is to study the microstrucutre and texture of Yttrium-Nickel- Borocarbide and Samarium-Cobalt thin film heterostructures prepared by Pulsed Laser Deposition and to establish structure-property relations for these materials in order to improve their properties and design new structures. Coincidence site lattice epitaxy was explored in most of these heterostructures (substrate, buffer and film) and studied in detail for each case. Epitaxial thin films of the superconducting borocarbide compound YNi2B2C were grown on single crystal MgO (100) substrates without and with Y2O3 buffer layer using pulsed laser deposition (PLD). In both cases YNi2B2C grows with [001] normal to the substrate. However, the in-plane texture depends on the starting condition. For samples without buffer layer, oxygen from the substrate diffuses into the film and forms an Y2O3 reaction layer at the interface. As a consequence, a deficiency of Y is generated giving rise to the formation of secondary phases. On the other hand, using an artificial Y2O3 buffer layer secondary phases are suppressed. The texture of the Y2O3 layers determines the texture of the YNi2B2C film. The superconducting properties of the borocarbide films are discussed with respect to texture and phase purity. To prevent the formation of an impurity phase at the interface, it was the aim of this preliminary investigation to study YNi2B2C films deposited onto single crystal MgO (100) substrates with an Ir buffer layer. The Ir buffer layer shows a strong cube-on-cube texture onto MgO(100) and also prevents the formation of an Y2O3 interlayer. However, during deposition of YNi2B2C the buffer layer disappears by Ir diffusion into the borocarbide film. The YNi2B2C film exhibits a c-axis texture consisting of four components. As a consequence of these effects, the superconducting transition Tc90 equals up to 13K, but with a transition width of 4K. In the second part of this work, hard magnetic Sm-Co/Cr films were epitaxially grown on MgO(100) and (110) substrates. They were characterized by X-ray pole figure measurements and transmission electron microscopy. For films deposited on MgO(100) at 700ºC, orientations are found with the c-axis aligned in-plane and out-of-plane. By lowering the deposition temperature to 370ºC, the out-of-plane orientations disappeared. Further lowering to 350ºC leads to the formation of amorphous regions in the SmCo5 film. For films grown on MgO(110) the Cr buffer deposition temperature plays an important role. When deposited at 700°C Cr(211) and (100) growth is observed leading to two different types of SmCo5 in-plane orientations. By lowering the Cr-buffer deposition temperature to 300ºC only one buffer and one SmCo5 orientation exists: Cr(-211)[0-11] and SmCo5(10-10)[0001]. The exact orientation relationships between substrate, buffer and films are explained and their correlation with magnetic properties are discussed.
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Gana, Usman Muhammadu. "A magnetic and structural study of CoCr-Pt,Ta alloy thin films." Thesis, University of Salford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281613.
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Deng, Yuanyuan, and 邓远源. "Magnetic circular dichroism and Hall measurement of cobalt-doped zinc oxide thin films." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B50434494.
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The observation of ferromagnetism of (Ga,Mn)As by Ohno in 1998 has inspired great interest in diluted magnetic semiconductors (DMS). DMS’s features combining ferromagnetism and semiconducting make them of great potential for conceptual spintronic devices, which is a promising field of research for the emerging electronics. The practical application of DMS requires a Curie temperature well above room temperature and an intrinsic ferromagnetism. There are several types of DMS materials. The typical ones are transition-metal (TM) doped GaAs, GaN and ZnO. The TM-doped ZnO has drawn particular attention due to the observation of room temperature ferromagnetism in this system including cobalt-doped ZnO.But the origin of ferromagnetic TM-doped ZnO is still unknown after a decade’s theoretical and experimental effort on this material.
In this thesis, we do the magnetic circular dichroism(MCD) and Hall measurement of high quality Cobalt-doped ZnO thin films grown by molecular beam epitaxy (MBE). Room temperature ferromagnetism is observed in these samples. Combining the data from MCD and Hall measurement, we attribute the room temperature ferromagnetism in this system to the impurity band of the doped Cobalt cations.published_or_final_version
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Master of Philosophy
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Takano, Kentaro. "Exchange anisotropy in thin film bilayers of nickel cobalt monoxide and various ferromagnetic materials /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 1998. http://wwwlib.umi.com/cr/ucsd/fullcit?p9820884.
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Mahvan, Nader. "Investigation into perpendicular anisotropy cobalt-chromium films with application to Winchester computer discs." Thesis, University of Plymouth, 1988. http://hdl.handle.net/10026.1/2588.
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RF-sputtered CoCr films have been characterized for a variety of deposition conditions, and the most effective parameters which bring about perpendicular anisotropy have been evaluated. In particular bias sputtering has been noted for its role in improving the crystallographic orientation and magnetic properties when applied to the substrate at certain values, hence the root mechanism of the observed improvement has been, as far as possible , investigated . These investigations have, in particular, focused on the extent to which impurity gases are likely to effect the magnetic properties of sputtered films, as well as quantifying the gas contents of the films using as yet unexploited (in this area) method of thermal desorption experiments. In a further attempt to quantify tolerable level of impurity species in the sputtering environment , impurity gases of nitrogen, oxygen and hydrogen, which are commonly present even in high vacuum systems, were intentionally introduced in the sputtering chamber and their effects on both magnetic and crystallographic properties of CoCr were noted . To measure the perpendicular and in-plane magnetic properties of CoCr , a combined polar-transverse Kerr magneto- optic system was costructed , through which direct magnetic measurement of CoCr/NiFe becomes feasible . This method was further exploited to compare volume and surface magnetic properties of CoCr , as measured using a V.S.M and this M-O system. Finally , a CoCr/NiFe W1nchester disc was fabricated on which a recording experiment was successfully performed.
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Espinosa, Jorge D. "Roughening of cobalt thin films on sapphire (110) upon annealing and superparamagnetic behavior of cobalt nanodots on sapphire (001)." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3801.
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Thesis (M.S.)--West Virginia University, 2004Title from document title page. Document formatted into pages; contains vi, 30 p. : ill. (some col.) Includes abstract. Includes bibliographical references (p. 29-30).
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Taylor, Anthony Park 1963. "Terbium iron cobalt diffusion barrier studies." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276931.
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Thin films (5nm ± 2nm thick) of ZrO2, Al2O3, TiO2, Sm, Gd, Zr, Ni, and Pt were deposited onto TbFeCo films (100nm ± 20nm thick) on silicon and graphite substrates and analyzed with XPS as prospective candidates for TbFeCo diffusion barriers. Metals were chosen primarily according to electronegativity. Samples were typically heated to 272°C in UHV for 20 hours to enhance diffusion. Experiments with the metals were performed in a more consistent manner than with the oxides. The Sm, Gd, and Zr were reactively oxidized during the deposition. The Sm/Sm-oxide and Gd/Gd-oxide appeared to be favorable candidates for TbFeCo diffusion barriers. TbFeCo was not detected near the surface before or after heating the samples to 272°C for 20 hours and depth profiles indicated oxygen contamination decreased steadily as the barrier/TbFeCo interface was approached. For the other materials examined, either the oxides were reduced (at least partially) during heating to 272°C (381°C for Al₂O₃) or diffusion of TbFeCo was detected after heating, indicating that they would not be favorable candidates for TbFeCo diffusion barriers.
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Chioncel, Mariana F. "Cobalt thin films produced by conventional and photo-assisted metal-organic chemical vapour deposition." Thesis, Keele University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327638.
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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.
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Fallon, Jason Michael. "The structure and properties of interface regions in nanostructured Co/Si thin films." Thesis, University of Salford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301415.
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Mattarello, Valentina. "Au-Co Thin Films and Nanostructures for MagnetoPlasmonics." Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3421781.
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This thesis develops in the framework of the Material Science for MagnetoPlasmonic purposes.
MagnetoPlasmonics is a recent and fast growing research _eld that aims at coupling the plasmonic properties typical of nanostructured noble metals (as, for instance, the local enhancement of electromagnetic _eld or the extraordinary optical transmission) with magnetic functionalities.
Promising applications, just to mention a few, span from sensing to the realization of active optical circuits at a nanoscale level.
MagnetoPlasmonic systems, so far mostly studied in the literature, are based on thin layers or nanostructures of noble metals coupled with ferromagnetic materials. Nevertheless, the requirement to increase the performances of such systems, and/or extend their functionalities, prompts the search for innovative compounds, which, displaying synergistic properties not otherwise achievable in phase segregated mixtures, can hold both plasmonic and magnetic features.
The aim of the present thesis is the realization and study of Au:Co alloyed thin _lms and nanostructures: gold is among the best performing materials in Plasmonics, while cobalt is known for its ferromagnetic properties. Unfortunately, the two metals are immiscible as bulk phases.
Au:Co thin _lms have been prepared by magnetron sputtering deposition technique in co-focusing geometry. Three di_erent compositions have been investigated, i.e., Au2Co1, Au1Co1 and Au1Co2, combined with three different values of thickness, i.e., ≈ 15 nm, ≈ 30 nm and ≈ 100 nm.
A full structural investigation has been carried out by X-Ray Di_raction integrated with XRay Absorption Spectroscopy and Transmission Electron Microscopy. The results demonstrate that the major fraction of the _lm is composed of an Au:Co alloy, typically richer in gold with respect to the nominal Au:Co atomic ratios.
The alloy fraction, its stoichiometry and the local order depend on the initial Au:Co ratio.
In the case of Au2Co1 sample, the alloy is, indeed, amorphous, while in the case of alloy richer in cobalt, there are some FCC crystalline seeds, elongated along the direction of the _lm growth. These grains are highly textured, with the (111) planes parallel to the substrate, and show a lattice constant that shortens as the Co content increases.
Besides this alloyed phase, there are segregated clusters of Cobalt, extremely nanostructured.
The presence of two magnetic phases is con_rmed by SQUID measurements, which, furthermore, allowed to characterize the hysteresis loops of the Au:Co _lms and to estimate the values of saturation magnetization.
The optical properties of the _lms have been characterized by transmittance UV-Vis measurements and Ellipsometry.
A thermal stability study demonstrated that the alloy is stable up to 200_ C; then, as the temperature increases, a de-alloying process occurs leading to two segregated phases of gold and cobalt.
The as-prepared Au-Co materials have been employed as metallic component in nanostructured periodic arrays, i.e., Semi Nano-Shell Array and Nano Hole Array. The morphological as well as the optical characterizations of the arrays demonstrate that these systems are promising candidates for future magneto-plasmonic studies and applications.Il presente lavoro si inserisce nell'ambito della scienza e ingegneria dei materiali per la MagnetoPlasmonica. Questa ultima è una recente, ma allo stesso tempo crescente, area di ricerca che mira a combinare le proprietà plasmoniche tipiche dei metalli nobili nanostrutturati (quali, ad esempio, l’intensificazione del campo elettromagnetico locale o la trasmissione ottica straordinaria) con funzionalità di tipo magnetico. Promettenti applicazioni spaziano dalla sensoristica alla realizzazione di nanocircuiti totalmente ottici, solo per citarne alcuni. Tradizionalmente i sistemi per MagnetoPlasmonica più considerati in letteratura prevedono l’accoppiamento di un film sottile o arrangiamento nanostrutturato di metalli nobili con materiale ferromagnetico. Tuttavia, al fine di migliorare le prestazioni di suddetti sistemi e/o esplorare nuove funzionalità è necessario ricercare nuovi composti in cui già il materiale innovativo presenta proprietà plasmoniche e magnetiche. Scopo della presente tesi è la realizzazione e lo studio di film sottili e nanostrutture a base di lega Au-Co: l’oro è, infatti, un metallo nobile tra i migliori per applicazioni in plasmonica e il cobalto è un materiale ferromagnetico. I due metalli allo stato bulk sono notoriamente immiscibili. Con la tecnica di deposizione magnetron sputtering sono stati depositati (in geometria di codeposizione) film sottili Au:Co, caratterizzati da tre diverse composizioni, ovvero Au2Co1, Au1Co1 e Au1Co2 e tre diversi spessori, rispettivamente ≈ 15 nm, ≈ 30 nm e ≈ 100 nm. Una ricerca estesa è stata condotta con l’obiettivo di studiare attentamente le proprietà strutturali dei film, combinando diffrazione a raggi X, con misure di Assorbimento X svolte al Sincrotrone e Microscopia elettronica. I risultati dimostrano che la parte predominante del film è costituita da una lega Au-Co che è tipicamente più ricca in oro rispetto ai rapporti atomici nominali di Au e Co. La frazione di lega, la sua stechiometria e l’ordine locale dipendono dal rapporto Au/Co inizialmente presente. Inoltre, mentre nel campione Au2Co1 la lega è prevalentemente amorfa, nel caso delle leghe più ricche in cobalto vi è la presenza di grani FCC cristallini, allungati lungo la direzione di crescita del film, fortemente tessiturati (in cui i piani (111) sono prevalentemente paralleli al substrato) e caratterizzati da un parametro reticolare che diminuisce all'aumentare del contenuto di cobalto. Oltre alla fase di lega, sono presenti dei clusters di cobalto, caratterizzati da un basso ordine strutturale. L’interfaccia tra due fasi magnetiche è stata confermata da misure SQUID che hanno inoltre permesso di caratterizzare i cicli di isteresi dei film Au:Co e di stimarne i valori di magnetizzazione di saturazione. Le proprietà ottiche dei film sono state caratterizzate con misure di trasmittanza (nel range UV-Vis) ed Ellissometria. Da un punto di vista termico, la lega Au-Co si dimostra stabile fino a 200° C; al crescere della temperatura ha lungo una de-alligazione che porta alla formazione di fasi metalliche separate di oro e cobalto. I materiali Au-Co così preparati e caratterizzati sono stati poi impiegati come componente metallica in array periodici nanostrutturati, i.e., Semi Nano-Shell Array e Nano Hole Array. Gli array sono stati caratterizzati da un punto di vista morfologico e ottico dimostrandosi promettenti piattaforme per future caratterizzazioni MagnetoPlasmoniche.
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Nallan, Himamshu, Thong Ngo, Agham Posadas, Alexander Demkov, and John Ekerdt. "Area Selective Deposition of Ultrathin Magnetic Cobalt Films via Atomic Layer Deposition." Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-207142.
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The work investigates the selective deposition of cobalt oxide via atomic layer deposition. Methoxysilanes chlorosilane and poly(trimethylsilylstyrene) self-assembled monolayers are utilized to prevent wetting of water and cobalt bis(N-tert butyl, N'-ethylpropionamidinate) from the substrate, thereby controlling nucleation on the substrate and providing a pathway to enable selective deposition of cobalt oxide. Sr and Al are deposited atop the oxide films to scavenge oxygen and yield carbon-free cobalt metal films. Thermal reduction of the oxide layer in the presence of CO and H 2 was also investigated as an alternative. Finally, we demonstrate control over the tunability of the coercivity of the resultant films by controlling the reduction conditions.
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Shihub, Salahedin Ibrahim. "Studies of the electrical and structural properties of organic semiconducting thin films of thermally evaporated cobalt phthalocyanine." Thesis, Keele University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301164.
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Timmermann, Felix [Verfasser], and Manfred [Akademischer Betreuer] Albrecht. "Structural and Electrical Investigations on Iron-Antimony and Cobalt-Antimony Thin Films / Felix Timmermann ; Betreuer: Manfred Albrecht." Augsburg : Universität Augsburg, 2021. http://d-nb.info/1228787913/34.
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Sharma, Shalini [Verfasser], Lambert [Akademischer Betreuer] Alff, and Oliver [Akademischer Betreuer] Gutfleisch. "Structural and magnetic properties of epitaxial rare-earth cobalt thin films / Shalini Sharma ; Lambert Alff, Oliver Gutfleisch." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2020. http://d-nb.info/1211726215/34.
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Deacon, Liam Matthew. "Structural, electronic and magnetic studies of polar zinc oxide surfaces and their interfaces with ultra-thin cobalt films." Thesis, University of Reading, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.625440.
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Zinc oxide (ZnO) has a desirable combination of opto-electronic properties that, when combined with magnetic transition metal dopants such as cobalt, place it at the forefront of next generation materials to harness both electron charge and spin in the field now known as spintronics. In this thesis the polar (0001) surfaces of ZnO single crystals are revisited and used as a basis for the growth of ultrathin cobalt films before subsequent processing in an effort to produce a CoZnO dilute magnetic semiconductor. A method using Zn sublimation partial pressures is given that provides reliable preparation of clean ZnO(0001) surfaces and comparisons between these two surface terminations are made on the basis of LEED, STM, UPS and XPS arguments.
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Kenny, Leo Thomas. "Preparation and characterization of lithium cobalt oxide by chemical vapor deposition for application in thin film battery and electrochromic devices /." Thesis, Connect to Dissertations & Theses @ Tufts University, 1996.
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Thesis (Ph.D.)--Tufts University, 1996.Adviser: Terry E. Haas. Submitted to the Dept. of Chemistry. Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Roy, Nirmita. "Electrical, Optical and Thermal Investigations of Cobalt Oxide-Antimony Doped Tin Oxide (CoO-ATO) Thin Films and Nanofiber Membranes." Scholar Commons, 2017. https://scholarcommons.usf.edu/etd/7441.
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The main aim of this thesis work is to investigate the electrical, optical and thermal impact characteristics of cobalt oxide doped antimony tin oxide (CoO-ATO) in the form of thin films and nanofiber membranes. CoO-ATO is a novel composite material that has the potential to be used as reinforced aircraft coatings, military garment coatings, or more specifically as an anti-reflective (AR) top coating for photovoltaic (PV) cells. This work will be critical in determining the effectiveness of using a CoO-ATO layer in these applications. Electrospun nanofibers and spin coated thin films consisting of a polymeric solution of CoO-ATO will be used. Thin films are created using spin coating techniques, and nanofiber membranes are created using an electrospinning technique. Polystyrene (PS) will be used as a solute, and chloroform as a solvent, to create the solution. It is hypothesized that coatings of this material will have improved optical characteristics as compared to traditional ATO coatings and minimum impact from thermal cycling making it a favorable candidate for PV cells. This work will do an electrical, optical and thermal cycling impact characterization of CoO-ATO thin films and nanofiber membranes for a doping range of x% CoO where x ranged from 0.2
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Mackay, Kevin George Hamilton. "Fabrication and characterisation of high moment thin films for inductive write heads." Thesis, Queen's University Belfast, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314178.
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Zschiesche, Hannes. "Formation and segregation in cobalt silicide and manganese germanide thin films : correlative study by electron microscopy and atom probe tomography." Electronic Thesis or Diss., Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0219.
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Dans cette thèse, des formations des germaniures de manganèse et des disiliciures de cobalt en couche minces ont été étudié comme la structure et chimie. Dans le système Mn-Ge, deux nouvelles relations entre des grains du Mn5Ge3 et (111)Ge ont été identifiées. De plus, il a été montré que la pureté du Mn5Ge3 dans les couches déposées par pulvérisation cathodique magnétron dépend du mécanisme de croissance. Une diffusion réactive donne du Mn5Ge3 presque pure tandis qu’une réaction non-diffusive donne du Mn5Ge3 qui contient la plupart des impuretés de la pulvérisation cathodique magnétron. Dans CoSi2 qui a été formé d’une configuration Co/Ti/Si, une ségrégation du Ti a été détectée dans les joints de grains du CoSi2. En outre, la distribution du Ti ségrégé a été caractérisée d’être inhomogènes. Pour étudier la ségrégation dans les joints de grains systématiquement, une méthode a été développé qui permet de corréler des investigations structurelle et chimie à l’échelle atomique sur un et le même échantillon dans les joints de grains sélectionnes. Finalement, une méthode a été proposée pour quantifier une ségrégation dans les points tripleGermanide and silicide thin films have application in different field such as thermoelectricity, magnetism and/or microelectronics. This PhD thesis study the formation, structure and chemistry of Mn5Ge3 thin films, which is interesting due to its ferromagnetic property for possible spintronic devices, and of CoSi2 thin films, which are used as contact materials. Two new epitaxial relationships between Mn5Ge3 grains and (111)Ge have been identified. The chemical purity of Mn5Ge3 has been related to the deposition by magnetron sputtering: Mn5Ge3 thin films grown by reactive-diffusion are relatively pure while the significant incorporation of impurities in Mn5Ge3 grown by non-diffusive reaction is beneficial for the ferromagnetic property. Ti segregation to CoSi2 grain boundaries has been quantified in CoSi2 grown from a Co/Ti/Si thin film. Additionally, an inhomogeneous distribution of Ti at CoSi2 grain boundary has been related to the defect density. A method has been developed for correlative structural and chemical investigations at the atomic scale on selected interfaces. Finally, a method to quantify the triple junction segregation has been proposed
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Butterfield, Martin Thomas. "Surface structure of ultrathin metal films deposited on copper single crystals." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/33132.
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Ultrathin films of Cobalt, Iron and Manganese have been thennally evaporated onto an fcc Copper (111) single crystal substrate and investigated using a variety of surface structural teclmiques. The small lattice mismatch between these metals and the Cu (111) substrate make them an ideal candidate for the study of the phenomena of pseudomorphic film growth. This is important for the understanding of the close relationship between film structure and magnetic properties. Growing films with the structure of their substrate rather than their bulk phase may provide an opportunity to grow materials with novel physical and magnetic properties, and hence new technological applications. Both Cobalt and Iron have been found to initially maintain a registry with the fee Cu (111) surface in a manner consistent with pseudomorphic growth. This growth is complicated by island rather than layer-by-layer growth in the initials stages of the film. In both cases a change in the structure of the film seems to occur at a point where the coalescence of islands in the film may be expected to occur. When the film does change structure they do not form a perfect over-layer with the structure of their bulk counterpart. The films do contain a number of features representative of the bulk phase but also contain considerable disorder and possibly remnants of fcc (111) structure. The order present in these films can be greatly improved by annealing. Manganese appears to grow with an fee Mn (111) lattice spacing and there is no sign of a change in structure in films of up to 4.61 ML thick. The gradual deposition and annealing of a film to 300°C, with a total deposition time the same as that for a 1 ML thick film, causes a surface reconstruction to occur that is apparent in a R30° (√3×√3) LEED pattern. This is attributed to the formation of a surface alloy, which is also supported by the local expansion of the Cu lattice in the (111) direction.
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Kretzschmar, B. S. M., K. Assim, Andrea Preuß, A. Heft, Marcus Korb, Marc Pügner, Thomas Lampke, B. Grünler, and Heinrich Lang. "Cobalt and manganese carboxylates for metal oxide thin film deposition by applying the atmospheric pressure combustion chemical vapour deposition process." Technische Universität Chemnitz, 2018. https://monarch.qucosa.de/id/qucosa%3A21422.
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Coordination complexes [M(O2CCH2OC2H4OMe)2] (M = Co, 4; M = Mn, 5) are accessible by the anion exchange reaction between the corresponding metal acetates [M(OAc)2(H2O)4] (M = Co, 1; M = Mn, 2) and the carboxylic acid HO2CCH2OC2H4OMe (3). IR spectroscopy confirms the chelating or μ-bridging binding mode of the carboxylato ligands to M(II). The molecular structure of 5 in the solid state confirms a distorted octahedral arrangement at Mn(II), setup by the two carboxylato ligands including their α-ether oxygen atoms, resulting in an overall two-dimensional coordination network. The thermal decomposition behavior of 4 and 5 was studied by TG-MS, revealing that decarboxylation occurs initially giving [M(CH2OC2H4OMe)2], which further decomposes by M–C, C–O and C–C bond cleavages. Complexes 4 and 5 were used as CCVD (combustion chemical vapour deposition) precursors for the deposition of Co3O4, crystalline Mn3O4 and amorphous Mn2O3 thin films on silicon and glass substrates. The deposition experiments were carried out using three different precursor solutions (0.4, 0.6 and 0.8 M) at 400 °C. Depending on the precursor concentration, particulated layers were obtained as evidenced by SEM. The layer thicknesses range from 32 to 170 nm. The rms roughness of the respective films was determined by AFM, displaying that the higher the precursor concentration, the rougher the Co3O4 surface is (17.4–43.8 nm), while the manganese oxide films are almost similar (6.2–9.8 nm).
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Lardjane, Soumia. "Etude des propriétés structurales, électroniques et magnétiques du semi-conducteur magnétique dilué : ZnO dopé au Cobalt." Phd thesis, Université de Technologie de Belfort-Montbeliard, 2013. http://tel.archives-ouvertes.fr/tel-01005359.
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La spintronique est un nouveau domaine de recherche qui exploite l'influence de la caractéristique quantique de l'électron (le spin) sur la conduction électrique. Pour réaliser des composants de spintronique innovants, l'obtention des semi-conducteurs ferromagnétiques à température ambiante devenait un challenge international. Dans ce contexte, après les premières prédictions théoriques de la haute température de Curie de Zn1-xCoxO et les rapports contradictoires sur l'état magnétique de ce système, nous nous sommes attaché à étudier le semi-conducteur magnétique dilué Zn1-xCoxO. Une étude ab initio des propriétés structurales, électroniques et magnétiques du Zn1-xCoxO a été effectuée en utilisant la méthode de pseudopotentiels dans le cadre de la théorie de la fonctionnelle de la densité (DFT) avec les deux approximations GGA et GGA+U. En parallèle, des films minces de Zn1-xCoxO ont été synthétisés par co-pulvérisation cathodique magnétron en condition réactive avec différentes conditions d'élaboration. Les propriétés structurales, morphologiques, électriques et magnétiques ont été analysées par différentes techniques de caractérisation et confrontées à celles obtenues par l'étude ab inito.
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Wilson, Leon Kerr. "The study of transition metal surfaces and thin films with inverse photoemission and scanning tunnelling microscopy." Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367084.
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Stichauer, Libor. "Étude des propriétés optiques et magnéto-optiques de films nanocristallins de ferrite de cobalt." Nancy 1, 1994. http://www.theses.fr/1994NAN10365.
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Ce mémoire concerne l'étude des propriétés optiques et magnéto-optiques dans le domaine visible proche infrarouge, de films de ferrite de cobalt de structure nanocristalline. Nous avons en particulier déterminé le coefficient d'absorption et la rotation faraday. Les films sont préparés par pulvérisation cathodique radiofréquence de cibles d'oxydes en présence d'un faible flux d'oxygène. Ce matériau est un support potentiel d'enregistrement magnéto-optique à haute densité. L'obtention des spectres d'absorption des films à partir des données spectrophotometriques a nécessité la mise au point d'une méthode spécifique de dépouillement des données. Les résultats obtenus montrent l'existence de désordres topologique et magnétique croissant avec le flux d'oxygène, ce qui a déjà été révélé par des techniques macroscopiques. Les résultats originaux sont la mise en évidences d'une brisure de symétrie de l'environnement octaédrique des cations, et l'existence du désordre magnétique sur les deux sites cationiques du spinelle. Ceci doit servir de guide à une étude microstructurale approfondie
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Andrade, Gustavo Fernandes Souza. "Adsorção molecular em metais de transição (ferro, cobalto e níquel) monitorada pela técnica de espalhamento Raman intensificado pela superfície: diferentes tipos de substratos metálicos." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/46/46132/tde-24102007-134700/.
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Nesta tese de doutorado foram desenvolvidas metodologias para obter espectros Raman intensificados pela superficie de adsorbatos orgânicos em eletrodos de Fe, Co e Ni, que são metais que apresentam baixo fator de intensificação SERS. Foram desenvolvidos procedimentos de ativação eletroquímica para eletrodos puros dos três metais. Os protocolos de ativação eletroquímica foram utilizados para obter espectros SERS de piridina, 1,10-fenantrolina e 2- e 4-aminopiridina. O fator de intensificação determinado para o três metais, da ordem de 102-103 vezes, depende fortemente do modo vibracional do adsorbato. Os espectros SERS da piridina nos metais de transição, quando comparados com os cálculos de espectros vibracionais de cluster da piridina com átomos metálicos por DFT mostram que a formação do radical α-piridil com a adsorção nos metais de transição, proposta na literatura, não ocorre. Os perfis de excitação SERS calculados pelo modelo de transferência de carga da piridina apresentaram boa correlação com os dados experimentais. Os resultados SERS para a 1,10-fenantrolina mostraram que a espécie que adsorve é a molécula livre, com a espécie adsorvida semelhante ao complexo sintetizado. A dependência das intensidades relativas com o potencial nos espectros SERS é diferente da observada para os espectros Raman ressonante dos complexos da phen com metais de transição, mostrando que o estado excitado monitorado pelas duas técnicas é diferente. O monitoramento da adsorção das 2-aminopiridinas nos metais de transição permitiu sugerir a adsorção pelo anel piridínico para potenciais menos negativos e através dos nitrogênios piridínico e amínico para potenciais mais negativos em eletrodos de Co e Ni, e para o Fe adsorve apenas pelo nitrogênio piridínico. Em solução eletrolítica 0,1 mol.L-1 KCl, a 4-aminopiridina passa de fracamente ligada para um complexo de superficie semelhante ao complexo sintetizado para potenciais mais negativos. Utilizando a solução eletrolítica 0,1 mol.L-1 KI, as duas espécies são observadas para um intervalo maior de potenciais. No eletrodo de Ni, observa-se 4-aminopiridina protonada para E = -0,7 V; para potenciais mais negativos um complexo de superficie semelhante ao complexo sintetizado é observado. Os filmes eletrodepositados de Co e Ni em eletrodos de Ag ativado eletroquimicamente permitiram a obtenção de espectros SERS da py com alto fator de intensificação. Os filmes com espessuras maiores que 2 monocamadas de Co ou Ni apresentaram bandas intensas da piridina adsorvida nestes metais, sem bandas da piridina adsorvida em Ag, indicando que os filmes não apresentam pinholes, com intensidade SERS 100 vezes maior do que os metais puros. As intensidades relativas dos espectros SERS são similares à obtidas nos espectros SERS da piridina nos metais puros para filmes finos mais espessos do que 7 monocamadas. Foram construídos substratos de Au SERS-ativos com alto desempenho e reprodutibilidade por eletrodeposição sobre uma máscara de microesferas de poliestireno. Os espectros SERS da 4-mercaptopiridina adsorvida nos substratos otimizados apresentaram intensidade 2 vezes maior do que o eletrodo de Au ativado eletroquimicamente. A reprodutibilidade do sinal SERS para estes substratos foi de ± 15 %, indicando que estes substratos podem ser utilizados como sensores para sistemas de interesse analítico.Surface-enhanced Raman spectra of organic adsorbates on Fe, Co and Ni electrodes were acquired after the development of specific methodologies described in this PhD thesis. Electrochemical activation procedures were developed for the three bare metaIs electrodes. The electrochemical activation protocols were applied for the acquisition of SERS spectra of pyridine, 1,10-phenanthroline and 2- and 4-aminopyridine on Fe, Co e Ni electrodes. The total and relative intensities changes of SERS bands with the applied potentials were explained by the charge transfer mechanism, which had a large contribution in the SERS enhancement for these metaIs. The enhancement factor determined for the three metaIs, on the 102-103 times range, strongly depends on the adsorbate\' s vibrational modes. The SERS spectra of pyridine on the transition metals and vibrational spectra calculations of pyridine with metallic atoms showed that the formation of α-pyridil in the adsorption on transition metaIs, suggested in the literature, didn\'t occur. The calculated pyridine SERS excitation profiles present reasonable correlaton with the experimental data. The SERS results for 1,10-phenanthroline showed that the free molecule was the adsorbing species. The potential dependence of the SERS relative intensities was different from those of the resonance Raman spectra of 1,10-phenanthroline complexes with transition metal ions, indicating that different excited states were probed by the two techniques. 2-aminopyridine adsorbed through the pyridinic ring at less negative potentials and through both pyridinic and aminic nitrogens at more negative potentials on Co and Ni electrodes, but for Fe electrode it adsorbed exclusively through the pyridinic nitrogen. 4-aminopyridine adsorbed perpendicularly to the electrode. In 0,1 mol.L-1 KCl electrolytic solution, 4-aminopyridine changed from weak1y bound to a surface complex similar to the synthesized complex at more negative potentials. In 0,1 mol.L-1 KI electrolytic solution, both species were observed in a larger potential interval. On the Ni electrode, protonated 4aminopyridine was observed for V = -0.7 V, and for more negative potentials a surface complex, similar to the synthesized one, was observed. The electrodeposition of ultrathin film of Co and Ni on electrochemically-activated Ag electrodes allowed obtaining SERS spectra of pyridine with high enhancement factors. The SERS spectra of py for films thickness higher than 2 monolayers of Co or Ni presented intense bands of pyridine adsorbed on these metals, and no bands of pyridine adsorbed on Ag were observed, indicanting the absence of pinholes in the films. The relative intensities of SERS spectra on the thin films were similar to those obtained for the SERS of pyridine on the bare metaIs electrodes for films thicker than 7 monolayers, but with SERS intensity 100 times higher. The SERS activity and signal strength reproducibility of Au nanostructured substrates obtained by electrodeposition on a polystyrene masking were evaluated. The SERS spectra of 4-mercaptopyridine adsorbed on optimized electrodes presented intensities 2 times greater than those of the electrochemically activated Au electrode. The SERS intensity reproducibility for these substrates was ± 15%, indicating the potential use of such substrates as sensors.
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Mukherjee, Devajyoti. "Growth and Characterization of Epitaxial Thin Films and Multiferroic Heterostructures of Ferromagnetic and Ferroelectric Materials." Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3622.
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Multiferroic materials exhibit unique properties such as simultaneous existence of
two or more of coupled ferroic order parameters (ferromagnetism, ferroelectricity,
ferroelasticity or their anti-ferroic counterparts) in a single material. Recent years have
seen a huge research interest in multiferroic materials for their potential application as
high density non-volatile memory devices. However, the scarcity of these materials in
single phase and the weak coupling of their ferroic components have directed the
research towards multiferroic heterostructures. These systems operate by coupling the
magnetic and electric properties of two materials, generally a ferromagnetic material and
a ferroelectric material via strain. In this work, horizontal heterostructures of composite
multiferroic materials were grown and characterized using pulsed laser ablation technique.
Alternate magnetic and ferroelectric layers of cobalt ferrite and lead zirconium titanate,
respectively, were fabricated and the coupling effect was studied by X-ray stress analysis.
It was observed that the interfacial stress played an important role in the coupling effect
between the phases. Doped zinc oxide (ZnO) heterostructures were also studied where
the ferromagnetic phase was a layer of manganese doped ZnO and the ferroelectric phase
was a layer of vanadium doped ZnO. For the first time, a clear evidence of possible room
temperature magneto-elastic coupling was observed in these heterostructures. This work
provides new insight into the stress mediated coupling mechanisms in composite
multiferroics.
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Clem, William Charles. "Mesenchymal stem cell interaction with nanonstructured biomaterials for orthopaedic applications." Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2009r/clem.pdf.
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Thesis (Ph. D.)--University of Alabama at Birmingham, 2008.Additional advisors: Yogesh K. Vohra, Xu Feng, Jack E. Lemons, Timothy M. Wick. Description based on contents viewed July 8, 2009; title from PDF t.p. Includes bibliographical references.
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Martin, Élodie. "Modulation de l'anisotropie dans le ferrite de cobalt en couches minces pour des applications en électronique de spin." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAE026/document.
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Le domaine de l’enregistrement magnétique est en constante évolution pour repousser davantage les limites de stockage de l’information, une approche prometteuse étant l’enregistrement perpendiculaire. Le matériau faisant l’objet de ce manuscrit est le ferrite de cobalt CoFe2O4 (= CFO). Ses propriétés font de lui un candidat prometteur pour la réalisation de dispositif à enregistrement perpendiculaire, cela passant par le contrôle de sa direction de facile aimantation.Ce travail de thèse traite ainsi de la modification de l’anisotropie magnétocristalline du CFO en couche mince par dopage aux éléments de terres rares. Nous avons démontré la possibilité de moduler la direction de facile aimantation du CFO non dopé, en modifiant la pression partielle en O2/N2 lors de l’élaboration. Nous avons également mis en évidence l’insertion des éléments lanthanides dans la structure du CFO ainsi que l’impact de l’anisotropie de la terre rare sur les propriétés magnétiques du matériauThe field of magnetic storage is in constant progress to constantly push further the storage capacity of the device. A promising approach is the perpendicular magnetic recording of datas. The material presented in this manuscript is cobalt ferrite. It is an excellent candidate for the realization of perpendicular storage device due to its properties. The present work deals with the modification of the magnetic anisotropy by doping the ferrite cobalt thin films with rare earth elements. We have demonstrated the possibility to modulate the easy magnetization axis of undoped cobalt ferrite by changing the partial pressure of O2/N2 during the elaboration of the thin films. We have also highlighted the insertion of rare earth elements into the structure of the cobalt ferrite although their important ionic radii. The impact of the rare earth anisotropy on the magnetic properties of the ferrite cobalt has also been observed
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Kim, Jiyeon [Verfasser], Roland A. [Gutachter] Fischer, and Anjana [Gutachter] Devi. "Organometallic chemistry of transition metal-group 13 complexes and metal-organic precursor synthesis for ALD cobalt oxide thin films / Jiyeon Kim ; Gutachter: Roland A. Fischer, Anjana Devi." Bochum : Ruhr-Universität Bochum, 2017. http://d-nb.info/1144613949/34.
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Carlomagno, Ilaria. "L'origine de la réponse magnétique particulière des films minces de Co intercalés entre Graphene et Ir(111)." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAY025/document.
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Le sujets de cette thèse sont l'évolution structurelle et la réponse magnétique particulière des films de cobalt observés lors de l'intercalation entre graphène et Ir (111).L'origine du comportement magnétique exotique de ces films n'a pas été trouvée encore. À cet égard, l'objectif final de ce travail est de sonder les effets de l'anisotropie structurale sur l'anisotropie magnétique.Plusieurs paramètres tels que l'épaisseur du film, les temps et les températures de la procedure du textit{annealing}, la présence de graphène et l'environnement local de Co ont été pris en compte comme possibles sources d'anisotropie structurale.Une analyse complète a été réalisée en utilisant des techniques complémentaires et avancées. Techniques comme la spectroscopie de photoélectrons de rayons X (XPS) et l'effet Kerr magnéto-optique (MOKE) ont fourni des informations sur la distribution de Co dans la direction perpendiculaire à la surface et sur la réponse magnétique. Cependant, techniques de rayonnement synchrotron comme la spectroscopie d'absorption de rayonnement X (XAS) et la diffraction de rayons X par incidence rasante (GIXD) ont sondé la structure locale et l'ordre à long terme des films.L'analyse présentée dans cette thèse inclut les effets de surface à l'interface Co/Ir, l'environnement local autour du Co, la structure cristalline du film, la rugosité du système et le désordre moyen.En particulier, l'évolution de ces paramètres est présentée et discutée en même temps que leur effet sur la réponse magnétique macroscopique des films intercalés.Les résultats démontrent que les traitements thermiques affectent la morphologie du Co, sa rugosité et sa coordination locale. Tels effets altèrent la structure du film affectant l'anisotropie magnétique globale. Cette information est utile à des fins applicatives. De plus, la description des modifications micro-structurales fournit un aperçu approfondi des propriétés physiques des films de Co intercalésThis thesis focuses on the structural evolution and the peculiar magnetic response of Cobalt films observed upon intercalation between Graphene and Ir(111).The origin of the exotic magnetic behaviour of such films cite{ROUGEMAILLE} has not been found yet. In this respect, the final goal of this work is to probe the effects of the structural anisotropy on the magnetic anisotropy.Several parameters such as: film thickness, annealing times and temperatures, Graphene presence, and Co local environment were taken into account as possible sources of structural anisotropy.A complete analysis was carried out using complementary, state-of-the-art techniques. While laboratory techniques such as X-ray Photoelectron Spectroscopy (XPS) and Magneto-Optic Kerr Effect (MOKE) provided information on the Co distribution along the direction perpendicular to the surface, and on the magnetic response, synchrotron radiation techniques such as X-ray Absorption Spectroscopy (XAS) and Grazing Incidence X-ray Diffraction (GIXD) probed the local structure and the long range order of the films.The analysis presented in this thesis includes the surface effects at the Co/Ir interface, the local Co environment, the crystalline structure of the film and the system roughness and average disorder.In particular, the evolution of such parameters is presented and discussed together with their effect on the macroscopic magnetic response of the intercalated films.The results demonstrate that thermal treatments affect Co morphology, roughness, and local coordination. Such effects alter the film structure affecting the overall magnetic anisotropy. This information alone is valuable for applicative purposes. Moreover, the description of the micro-structural modifications provides a deep insight into the physical properties of intercalated Co films
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COSTA, e. SILVA DANILO L. "Filmes finos de carbono depositados por meio da técnica de magnetron sputtering usando cobalto, cobre e níquel como buffer-layers." reponame:Repositório Institucional do IPEN, 2015. http://repositorio.ipen.br:8080/xmlui/handle/123456789/23916.
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Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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ROMERO, SERGIO A. "Producao e caracterizacao de filmes finos de SmCo." reponame:Repositório Institucional do IPEN, 2001. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10915.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Lawson, Thomas Ryan. "Micro-Raman spectroscopy and dry turning evaluations of nanostructured diamond films deposited on tungsten-carbide lathe inserts." Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2008m/lawson.pdf.
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SÁ, Luciano Vaz de. "Magnetostricção e Anisotropia Magnética de filmes de Cobalto em substratos de vidro e silício." Universidade Federal de Goiás, 2011. http://repositorio.bc.ufg.br/tede/handle/tde/806.
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Previous issue date: 2011-09-09The Ferromagnetic Resonance technique is used to study the magnetostriction and the magnetic anisotropy of cobalt thin films grown on glass and silicon substrates. The effective values of the magnetostriction and magnetic anisotropy constants obtained do not agree with known values in the literature, but show the viability of the experimental method used [with the film glued to a cantilever beam under stress] to study the magnetostriction of magnetic thin films.
Este trabalho tem como objetivo estudar a magnetostricção e a anisotropia magnética de filmes finos de cobalto usando a técnica de Ressonância Ferromagnética. As amostras investigadas foram produzidas pela técnica de magnetron sputtering, depositadas sobre substratos de vidro e silício, com espessuras variando na faixa de 10 a 20 nm. Os valores efetivos obtidos para as constantes de magnetostricção e de anisotropia magnética de volume e de superfície diferem de valores conhecidos na literatura, mas comprovam a viabilidade do procedimento experimental aplicado [com o filme fixo sobre uma haste cantilever sujeita a stress] para investigar a magnetostricção de filmes finos magnéticos.