Download or read book Microstructure and Magnetic Properties of Co CoO CoNiO 2 NiO and CoxN i 1 x CoO Nanocomposite Thin Films written by Jae-Young Yi and published by . This book was released on 2000 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microstructure and Magnetic Properties of Co CoO Nanocomposite Films written by Jae Y. Yi and published by . This book was released on 2001 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of exchange anisotropy on nanosize Co particles was studied in Co-CoO nanocomposite thin films for possible applications for magnetic storage media. XRD analyses showed nanosize hcp Co particles and (111) textured CoO phase. A broken columnar structure was observed in cross-section TEM images. Very large room temperature coercivity (^ 1 kOe) was observed and believed to be doe to a shape effect and possible local exchange coupling. Large exchange anisotropy at low temperatures and linear type temperature dependence were explained by finite size effects and thermal relaxation of the CoO particles. A slow decrease of thermoremanent moment (TRM) with temperature and large TRM at room temperature indicated that the exchange anisotropy significantly modified the anisotropy energy barrier of the Co crystallites in the CoO matrix. The results indicated that the exchange anisotropy could be used to stabilize nanosize ferromagnetic particles.

Download or read book Magnetic Properties and Microstructures of Ni80Fe20 CoxNi1 xO Exchange Coupled Thin Films written by Wei Cao and published by . This book was released on 1995 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structure Microstructure and Magnetic Properties of Electrodeposited Co and Co Pt in Different Nanoscale Geometries written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin films and nanowires of Co-Pt have been prepared by means of electrodeposition. Composition, structure, microstructure and magnetic properties have been intensively studied using X-ray diffraction, scanning electron microscopy and vibrating sample magnetometry and correlated to the deposition parameters such as electrolyte composition, deposition current and/or potential. Co rich Co-Pt films have been deposited at various current densities. A nearly constant composition of Co70Pt30 was achieved for current densities between 18 and 32 mA/cm2. Detailed texture measurements confirmed an increasing fraction of the hexagonal phase with its c-axis aligned perpendicular to the film plane with increasing current density. Accordingly, magnetic properties are strongly affected by the magnetocrystalline anisotropy of the hexagonal phase that competes with the shape anisotropy of the thin film geometry. Co-Pt nanowires have been prepared within alumina templates at different deposition potentials between -0.6 and -0.9VSCE changing the composition from nearly pure Pt to Co. The composition Co80Pt20 was observed at a deposition potential of -0.7VSCE. Co-Pt nanowires are nanocrystalline in the as-deposited state. Magnetic measurements reveal changing fcc and hcp phase fractions within the wires as the effective anisotropy significantly differs from the expected shape anisotropy for nanowires with high aspect ratio. This change in effective anisotropy is attributed to the preferential alignment of the c-axis of hcp Co-Pt phase perpendicular to the nanowires axis. A promising alternative with much smaller feature sizes is the diblock copolymer template. Electrodeposition of Co and Co-Pt into these templates has been carried out. Inhomogeneities in the template thickness as well as a certain substrate roughness have been identified to be the reasons for inhomogeneous template filling. Thus magnetic properties are dominated by large deposits found on top of the template. Additiona.

Download or read book Metal Oxides in Supercapacitors written by Deepak P. Dubal and published by Elsevier. This book was released on 2017-07-10 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal Oxides in Supercapacitors addresses the fundamentals of metal oxide-based supercapacitors and provides an overview of recent advancements in this area. Metal oxides attract most of the materials scientists use due to their excellent physico-chemical properties and stability in electrochemical systems. This justification for the usage of metal oxides as electrode materials in supercapacitors is their potential to attain high capacitance at low cost. After providing the principles, the heart of the book discusses recent advances, including: binary metal oxides-based supercapacitors, nanotechnology, ternary metal oxides, polyoxometalates and hybrids. Moreover, the factors affecting the charge storage mechanism of metal oxides are explored in detail. The electrolytes, which are the soul of supercapacitors and a mostly ignored character of investigations, are also exposed in depth, as is the fabrication and design of supercapacitors and their merits and demerits. Lastly, the market status of supercapacitors and a discussion pointing out the future scope and directions of next generation metal oxides based supercapacitors is explored, making this a comprehensive book on the latest, cutting-edge research in the field. Explores the most recent advances made in metal oxides in supercapacitors Discusses cutting-edge nanotechnology for supercapacitors Includes fundamental properties of metal oxides in supercapacitors that can be used to guide and promote technology development Contains contributions from leading international scientists active in supercapacitor research and manufacturing

Download or read book Microstructure and Magnetic Properties of Cobalt based Thin Films for Magnetic Recording written by Li Tang and published by . This book was released on 1992 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Magnetic Properties of Nanocomposite Cobalt based Thin Films written by J. Mark Meldrim and published by . This book was released on 2000 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Study of Magnetic Properties and Microstructure of Sputtered Co Cr Thin Films written by Yōichi Uchiyama and published by . This book was released on 1992 with total page 215 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structural and Magnetic Properties of Co Pt and Related Multilayer Thin Films written by Gerardo Antonio Bertero and published by . This book was released on 1995 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Magnetic properties and microstructure of ion implanted thin cobalt films written by Andrew Collin Campbell and published by . This book was released on 1985 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structural and Magnetic Properties of Co Mn Sb Thin Films written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin Co-Mn-Sb films of different compositions were investigated and utilized as electrodes in alumina based magnetic tunnel junctions with CoFe counterelectrode. The preparation conditions were optimized with respect to magnetic and structural properties. The Co-Mn-Sb/Al-O interface was analyzed by x-ray absorption spectroscopy and magnetic circular dichroism with particular focus on the element-specific magnetic moments. Co-Mn-Sb crystallizes in different complex cubic structures depending on its composition. The magnetic moments of Co and Mn are ferromagnetically coupled in all cases. A tunnel magnetoresistance ratio of up to 24% at 13 K was found and indicates that Co-Mn-Sb is not a ferromagnetic half-metal. These results are compared to recent works on the structure and predictions of the electronic properties.

Download or read book Microstructure and Magnetic Property of L1o CoPt 20 At C Magnetic Thin Film written by D. Y. Oh and published by . This book was released on 2003 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The CoPt-20at.%C thin films of 20nm thickness were sputter-deposited in the form of CoPt/C(n) (n=1: carbon layer thickness=4nm; n=4: each carbon layer thickness=1nm) and were transformation-annealed at 650 degrees C for various times. Carbon was found to dissolve into CoPt lattice and enlarge the c/a ratio of the ordered CoPt lattice. The amount of carbon dissolution increases with the decreasing carbon layer thickness at a given total carbon concentration. The carbon dissolution larger than a critical amount can lead to a shift of the phase equilibrium of ordering and produce a stable fine two-phase mixture of ordered and disordered phases at the equi-atomic composition of Co:Pt. This results in a fine and uniform stagnant grain structure of about 20nm on annealing at 650 degrees C. The carbon dissolution by increasing the c/a ratio of the ordered CoPt lattice reduces both the saturation magnetization and the magnetocrystalline anisotropy constant of the film and leads to a reduction of coercivity of CoPt films.

Download or read book Magnetic Exchange Coupling in Hard soft Ferromagnetic Composite Thin Films of CoPt Co written by Jihwan Kim and published by . This book was released on 2001 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of magnetic exchange coupling in nanocomposites of magnetically-hard phases combined with magnetically-soft phases is important for the development of high-performance permanent magnets. The present work aimed to elucidate the microstructure-exchange coupling relationship in model hard/soft bilayers of CoPt(L10, hard)/Co(soft) in both the as-deposited and annealed states. The CoPt layer (25--100 nm) was deposited at room temperature and annealed at 700°C to develop the magnetically hard, ordered L1 0 structure prior to room-temperature deposition of Co (2.8--225 nm). The transformation from FCC to L10 in CoPt was accompanied by grain growth and evolution of a & lang;111 & rang; fiber texture. The L1 0 mean domain area reached approximately one sixth of the mean grain area in nearly-fully and fully ordered CoPt. The coercivity of CoPt and the contribution of a pinning-type mechanism to the coercivity increased with increasing annealing time, concurrent with the increase in L10 fraction. In CoPt/Co bilayers, Co exhibited a & lang;0001 & rang; fiber texture. For as-deposited bilayers, the exchange length of Co was close to the magnetic domain wall width for CoPt. Annealing the bilayers at 300--450°C resulted in minor microstructural changes, increased the extent or strength of coupling and thereby enhanced the reversal coherency of the bilayers such that a Co layer of twice the CoPt domain wall width was fully coupled to the CoPt. Note that in bilayers with robust coupling both phases are affected, i.e., the magnetically-hard phase is exchange-softened, while the magnetically-soft phase is exchange-hardened. In contrast to lower-temperature anneals, annealing at 500--550°C, or for extended periods at 450°C, resulted in interdiffusion of Co and CoPt, consumption of the latter and formation of two new FCC and HCP Co-Pt solid solutions. These interdiffused bilayers showed an increased reversal coherency and a highly developed out-of-film plane anisotropy. When the magnetic and microstructural data are considered together, this study shows that the properties of hard/soft nanocomposites depend not only on the dimensions of both phases, but also on the physical and magnetic characteristics of each phase. A most significant outcome of this work is the demonstration that exchange coupling may be altered, and perhaps tailored, by processing-induced changes in the interphase interface.

Download or read book Area selective Deposition of Ferromagnetic Cobalt Films written by Zizhuo Zhang and published by . This book was released on 2018 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cobalt is a classic ferromagnetic material and finds applications in magnetic random access memory devices. As an emerging patterning technique, area-selective atomic layer deposition (AS-ALD) of cobalt films has the advantages of low cost and low film damage compared with the current patterning approach of photolithography followed by etching of cobalt films. This research explores the routes to realize the AS-ALD of ferromagnetic cobalt films. Carbon-free Co films have been deposited on MgO(001) and SiO2/Si substrates by low temperature thermal ALD of CoO and subsequent low temperature atomic deuterium reduction of CoO. While high temperature D2 reduction of CoO results in rough and disconnected Co islands, low temperature D reduction of CoO produces smooth and continuous Co films. The Co films produced by low temperature D reduction exhibit a smaller coercivity than the Co films produced by high temperature D2 reduction. Reduction conditions affect the microstructure and the magnetic properties of the reduced Co films. The process-structure-property relationship has been elucidated. The increase of reduction temperature, partial pressure of deuterium, and reaction time increases the average grain size and coercivity of the reduced Co films. Co films that are grown on substrates with lower dewetting tendency, such as MgO and Al2O3, show smaller average grain size and smaller coercivity. Polystyrene (PS) has been proposed to work as a passivation material to realize the AS-ALD of cobalt films. PS is effective in inhibiting the nucleation and film growth of CoO on oxide substrates. Micro-patterns and nano-patterns of CoO have been grown by AS-ALD through PS templates produced by photolithography and PS templates created by directed self-assembly of diblock copolymer, respectively. CoO patterns can be further reduced to form Co patterns without deformation.