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Patterned magnetic films are of interest for storing and sensing information, and possible logic applications, and find commercial applications in consumer goods such as personal computers. This thesis addresses the fast magnetic patterning of capped ultrathin Ni(_81)Fe(_19) films in Chapter 5, and the patterning and controlled magnetic switching of planar nanowires in Chapter 4. Controlled domain wall switching of complex wire geometries with comer structures, artificial trapping sites, 3-terminal junctions and more complex wire circuits is described in Chapters 6-7.The magnetic switching of planar Ni(_81)Fe(_19) nanowires fabricated by 30 keV, focused ion beam Ga(^+) ions was investigated, in the width range 60-500 nm. Experimentally measured wire easy axis coercivity is inversely proportional to width, similar to Stoner-Wohlfarth switching behaviour. Angular switching data for wires is presented. Significantly, wire coercivity and anisotropy field are shown to be strongly dependent on the ion beam raster direction during wire fabrication. The controlled propagation of head-to-head domain walls in a 27 Hz anticlockwise rotating magnetic field, through smoothly rounded comers is experimentally demonstrated. Domain wall propagation fields, 7 ± 3 Oe, just above the intrinsic domain wall coercivity were found. Using an L-shaped rounded comer geometry, the magnetic fields at which domain walls are introduced into wires and the domain wall propagation field were separated. Reproducible pinning and depinning of single domain walls on artificial domain wall traps with depths from 35-125 nm is demonshated.3-Terminal continuous Ni(_81)Fe(_19) wire junctions, suitable for AND/OR domain wall logic operations are described, in which the magnetic switching field of the device output is strongly dependent on the number of domain walls (0, 1, or 2), at the junction. An operating field phase diagram is presented in the context of junction integration with existing domain wall logic elements. Capped NigiFei9 films were ferromagnetically quenched by radiation induced transport of bilayer interfacial atoms. For Si/ Ni(_81)Fe(_19)/Al or Si/ Ni(_81)Fe(_19)/Au bilayers, the critical Ga(^+) ion dose to quench ferromagnetic ordering (Φ), measured by the magneto-optical Kerr (MOKE) effect, is demonstrated to be linearly proportional to the square of NigiFei9 thickness, (tNiFe)(^2) Therefore ultrathin-capped Ni(_81)Fe(_19) films can be magnetically quenched at ion doses ~ an order of magnitude lower then Ni(_81)Fe(_19)/Si samples, which are typically patterned by radiation sputtering from the vacuum- surface interface. Bilayer coercivity, uniaxial anisotropy field, remanent magnetization, and saturation magnetization as measured by MOKE, were tailored by controlled localized ion doses. Ga(^+) ion doses as low as 8 x 10(^13) ions.cm(^-2) reproducibly quenched measured room temperature ferromagnetism in 2 nm thick buried (_81)Fe(_19) films. Patterning of 200 nm wide in-plane magnetized wires embedded between a non magnetic cap and substrate is demonstrated.

A study of exchange biased systems has been made focused on the development of measurement protocols that yield measurement reproducibility. The materials studied were IrMn(tAF)/CoFe(10nm) thin films, with tAF being 3nm and 5nm. These materials were selected due to their industrial applications. The thicknesses were chosen as they were the most appropriate for the purpose of this study. Vibrating sample magnetometry has been used to investigate thermal activation properties in the set of samples. The measurement protocols developed allowed measurement reproducibility. They lead to a better understanding of the exchange biased phenomenon. It was found that the changes occurring in the exchange biased systemsd uring measuremenat re due to thermal activation in the antiferromagneticl ayer which reduced the degree of order within the antiferromagnet. It was observed that the peak in the coercivity with the temperature of thermal activation does not correlate with the median blocking temperature. A study of training effects and their behaviour with temperature has led to the identification of three different contributions to exchange bias which are spin freezing, spin reorientation, and thermal activation. Each of these effects contribute to the shift of the hysteresis loop and the coercivity of exchange biased systems through different mechanisms. The results obtained are consistentw ith a grain size dependenceo f the exchangeb ias phenomenon, and are in accordance with grain models of exchange bias. Also, the measurement protocols obtained have been used by other researchers in FeMn/NiFe exchange coupled bilayers. The results obtained were in accordance with the conclusions of this thesis.

X-ray scattering has been used to determine the alloy structure of GdFe2 and the real-time formation of nanoparticle assemblies. Initial growth curve analysis on the individual deposition of Gd and Fe allowed the correct stoichiometric ratio of the two species to be co-evaporated and annealed to form the alloy structure GdFe2- The structure of the [1/3 1/3] reconstruction has been determined. The Patterson map obtained from the structure factors at zero perpendicular momentum transfer shows that the Fe atoms are laterally displaced from their predicted positions. Structure factor data for the out-of-plane atomic positions shows that the Gd atoms sit in adsorption sites that are 22% higher than predicted hard sphere positions. Gold nanoparticles of various sizes coated with organic thiol molecules have been studied by X-ray diffraction. The self-assembly process on to a Si(III) substrate was probed in real-time by GISAXS which showed for the first time that the largest particles drop out of solution first and act as seeds for the smaller particles which infringe on the surface minutes later surrounding the larger particle domains. The intermixing of two particles with average size ratio 0.58 showed evidence for a self-assembled bimodal alloy structure which was indicated by missing intensity from a 2 peak Gaussian fit which could be accommodated for by a central 3rd peak. Self-assembly of thiol stabilised gold nanoparticles has been shown to occur at the solvent-air interface. The quality of self-assembly depends strongly on the size of the particles and the evaporation rate of the solvent. A random walk model was used to explain that as the solvent evaporation rate is significantly slowed the nanoparticles are restricted to vertical diffusion only but at room temperatures the particles can diffuse in all directions a result that is further emphasized by the increased level of ordering at cooler temperatures. A complete self-assembly procedure has been suggested where particles above a certain size (1 nm radius) can immediately self-assemble at the solvent-air interface to be later deposited on to the substrate where the thiol ligands can lock the particles into a tight self-assembled layer.

An investigation was made into the effect of rf magnetron deposition parameters on the resulting properties of chromium oxide thin films. The films were sputtered in an argon/ oxygen plasma environment with the main deposition parameters being the argon and oxygen flow rate, chamber pressure, deposition-time and the deposition power (forward and back). Tire effect of the sputter deposition regime which is controlled by the sputtering hysteresis phenomenon i.e. the reactive and metallic regimes, are expected to have a significant effect on the properties of the sputtered films and will have to be taken into account. The films were deposited on a range of substrates such as silicon, glass micro-slides and stainless steel 304 and the composition of the mainly amorphous sputtered films was determined through XPS, EDX and XRD. Optical characterisation and determination of optical constants was undertaken by transmission/reflection spectrophotometry, ellipsometry and Raman and FTIR analysis. Two designs of a solar thermal absorber (multilayer interference and tandem absorber) were designed and fabricated based on the optical constants measured by the methods previously stated and their performance analysed. The surface energy was calculated through measurement of the contact angle with three different liquids and the corrosion resistance of the films measured by OCP, linear sweep and EIS analysis in 3.5wt% NaCI solution. The mechanical properties were measured by nanoindentation, from which the hardness and elastic modulus of the samples could be obtained. The electrical properties were measured using a four point probe to calculate the thin film resistivity and the Kelvin probe analysis was used to measure the work function of the samples.

Hydroxyapatite (HA) is an important class of biomaterial which has been extensively researched as a coating on metallic implant devices and/or as a model for the study of cells on bioactive surfaces. The composition of such coatings, when compared with the raw HA target powder, has led to them being termed as calcium phosphate (CaP) thin films with varying "HA-like" properties. The ability of the coating to deliver some or all of the properties of the sources material is limited by the unit cell composition that originates from the crystallinity of the coating during its growth. Although structural models exist for HA as a powder, the unit cell composition of CaP thin films has not yet been determined at the level necessary to understand the influences that effects from substrate topography and thermal annealing have on these properties. This work describes a detailed investigation of the evolution of the microstructure that occurs via grain growth in sputter deposited CaP thin films. The approach taken here utilises a multi-source RF magnetron sputter deposition system to create the relevant CaP surfaces and the application of advanced characterisation techniques and data analysis methodologies to investigate the structural properties. The effects of the key operational aspect of the process, most particularly the sputtering parameters and subsequent thermal processing on the extent of stress incorporation determined from crystallographic data and quantitative phase analysis have indicated that the choice of deposition parameters is the most critical consideration in terms of coating reproducibility and quality. The relationship between quality of the precursor HA (target) powder, thickness of the deposited layer and the unit cell composition of coating have all been addressed. It has been shown that the composition of the coating and its evolving microstructure are determined through preferred crystallographic orientation in the plane of lowest surface energy which limits the size and angle of curvature of the grains present in the coating. The size and shape of the grains produced influences the distribution of residual stress levels, i.e. the mechanical stal)1ity of the coating and also the concentration of the various atoms that are distributed across and within the thin film.

This work presents investigations into the possibility of using the method of DC magnetron sputtering for the deposition of CuInSei (CIS) thin films. Two different approaches have been used for the suitability of manufacturing stoichiometric CIS layers. For both cases the target material consisted of non-stoichiometric CIS powder.