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The static and dynamic properties of spin distributions within domain walls(DWs) confined by Permalloy nanowire conduits are investigated by numerical simulations and high-speed magneto-optic polarimetry. Phase boundaries and critical points associated with DW spin distributions of various topologies are accurately determined using high-performance computing resources. Field-driven mobility curves that characterize DW propagation velocities in 20 nm thick nanowires are calculated with increasing the width of nanowires. Beyond the simple one-dimensional solution, the simulations reveal the four distinct dynamic modes. Oscillations of the field-driven DW velocity in Permalloy nanowires are observed above the Walker breakdown condition using high-speed magneto-optic polarimetry. A one-dimensional analytical model and numerical simulations of DW motion and spin dynamics are used to interpret the experimental data. Velocity oscillations are shown to be much more sensitive to properties of the DW guide structure (which also affect DW mobility) than the DW spin precessional frequency, which is a local property of the material. Transverse bias field effects on field-driven DW velocity are studied experimentally and numerically. DW velocities and spin configurations are determined as functions of longitudinal drive field, transverse bias field, and nanowire width. For a nanowire that supports vortex wall structures, factor of ten enhancements of the DW velocity are observed above the critical longitudinal drive-field (that marks the onset of oscillatory DW motion) when a transverse bias field is applied. The bias-field enhancement of DW velocity is explained by numerical simulations of the spin distribution and dynamics within a propagating DW that reveal dynamic stabilization of coupled vortex structures and suppression of oscillatory motion in the nanowire conduit resulting in uniform DW motion at high speed. Current-driven and current-assisted field-driven domain wall dynamics in ferromagnetic nanowires have thermal effects resulting from Joule heating, which make difficult to separate the spin-torque effects on DW displacements. To understand the thermal effects on DW dynamics, the temperature dependence of field-driven DW velocity is explored using high-bandwidth scanning Kerr polarimetry. Walker critical fields are decreased with increasing temperature and temperature-induced dynamic mode changes are observed. The results show that Joule heating effects are playing an important role in current-driven/current-assisted field-driven DW dynamics. / text

La nanotechnologie a pris un rôle clé dans le développement technologique actuel de façon extrêmement grande et interdisciplinaire. L'utilisation de nanofils dans la construction de structures/dispositifs plus complexe peut être entrevue en raison de sa polyvalence. Comprendre la fabrication de nanofils et être capable de les caractériser est extrêmement important pour ce développement. Des dispositifs à base de nanofils semi-conducteurs et ferromagnétiques ont été étudiés dans cette thèse, abordant les techniques de croissance et d'adressage pour des caractérisations électroniques et structurelles, et pour des développements à grande échelle pour des applications industrielles. Les nanofils de cobalt ont été électro déposés à différents pH permettant d'associer le pH de la solution à la caractérisation de la structure cristalline. Les nanofils de semiconducteurs ont été crus par CVD. L'adressage et l'alignement des nanofils ont été faits par diélectrophorèse couplé avec l'assemblage capillaire. Pour caractériser les nanofils, des techniques de lithographie optique et électronique ont été utilisés pour la fabrication des contacts. Une étude d'interface matériaux semiconducteurs/siliciure a été réalisée démontrant que les valeurs de barrière Schottky sont différentes entre des nanofils de silicium et des matériaux massifs. Dans le cas de nanofils InAs la barrière est imperceptible et il a été constaté que le fil de ZnO était de type p. Les applications ont démontrées différents dispositifs, tels que les transistors, les vannes de spin, capteurs de gaz, de l'humidité et de la lumière. Dans le cadre de vannes de spin, la caractérisation de l'interface semiconducteur/ferromagnétique a permis d'associer la valeur de la hauteur de barrière de Schottky à l'épaisseur de SiO2, qui agit comme une barrière à effet tunnel. Grâce aux mesures de transistors à effet de champ (FET) , nous avons pu identifier le type de porteurs de charge pour chaque matériau, extraire leur mobilité, la tension de seuil... Les capteurs ont été fabriqués à base de nanofils en Si, InAs, et ZnO, afin d'être utilisés comme capteurs de lumière, l'humidité et les gaz. Cette thèse propose une amélioration des technologiques actuelles d'adressage de nanostructures et l'utilisation des propriétés à l'échelle nanométrique pour des dispositifs plus efficaces et une large applicabilité, fournissant la base pour de futures études et les réalisations pratiques des nanosciences et des nanotechnologies. / Nanotechnology is at the center of nowadays technologies in an increasing and very interdisciplinary manner. Sticking together the manufacturing and characterization of the nano-devices and their constituent nanostructures are keys for the development of the field. This thesis covered studies of ferromagnetic (Co) and semiconductors nanowires (Si, InAs and ZnO) based nanodevices. Nanowires growing and correct addressing techniques were studied for measurements and characterizations set ups and for large-scale industrial applications possibilities. The growing techniques were electrodeposition and CVD. Different pHs were used for the solutions in the case of the Co nanowires growing that were, than, connected by means of electronic lithography. The resulting measurements enabled us to associate the pH to the crystalline structure characterization. The nanowires addressing was made using the dieletrophoresis technique coupled to capillary assembly and also by contacting the isolated nanowire by means of electronic lithography. The contact made in the nanowire was favored by the silicidation technique. For this two different materials, Pt and Ni, compatible with the CMOS technology. A deep study of the interface semiconductor/silicidation was performed and the Schottky Barrier of Si nanowires was verified to be smaller than the barrier in the bulk form of Si. In the InAs nanowires case an imperceptible barrier was found. The ZnO nanowires were found to be of p-type. The following devices were manufactured: top/back-gate transistors, lateral spin valves (local and non-local valves) and multilayer-nanowires based spin valves (local valves). The semiconductor nanowires sensors (gas, humidity and luminosity) were also manufactured and tested. In the spin valves context the interface semiconductor/ferromagnetic material was studied in order to associate the Schottky Barrier height to the SiO2 width that acts as a tunnel barrier. From the semiconductors nanowires based field effect transistors (FETs) measurements it was possible to verify the charge carriers type for each different material, to extract its mobility, threshold voltage and others. The manufactured sensors were made of Si, InAs and ZnO nanowires and the main aim was to use them as gas, humidity and luminosity sensors. The ZnO nanowires have been seen to be light sensitive whereas the Si and InAs nanowires responded to the presence of humidity and of pollutant gases, e.g. the NO2.