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. Dans-unepremì-eré-etape, En accord avec la littérature, les résultats de nosétudesnosétudes montrent desprobì emes spécifiques d'interprétation et de contrôle du magnétisme dans les systèmes d'oxyde dopés Dans unedeuxì emé etape, nous avons focalisé nos efforts sur la réalisation et l'´ etude de dispositifs spintroniques type jonction tunnel magnétique monocristallinè a base d'alliage full-Heusler Co 2 FeAl et debarrì ere tunnel de MgO(001) Les alliages Heusler sont réputés d'un point de vue théorique pour leur caractère demi-métallique qui se traduit par une polarisation de spin de 100%. Par uné etudeparalì ele cristallographique et magnétique, nous avons mis enévidenceenévidence une corrélation directe entre l'anisotropie structurale et les anisotropies magnétiques des couches minces d'alliage Co 2 FeAl En utilisant ces couches comme desélectrodesdesélectrodes magnétiques, nous avonsélaboré avonsélaboré, micro-structuré etétudiéetétudié des jonctions tunnel magnétiques cristallines Notre analyse a démontré que le transport tunnel polarisé en spin et la qualité de la demi-métallicité de l'alliage présentent une forte dépendance du grade de cristallinité du système Audeì a des aspects purement expérimentaux, cette thèse comporte desétudesdesétudes de modélisation analytique, numérique et ab-initio pour les propriétés magnétiques, ´ electroniques et de transport polarisé en spin des systèmes et dispositifsétudiésdispositifsétudiés. Mots-clés:Effet tunnel dépendant du spin, jonction tunnel magnétiqué epitaxiée, filtrè a spin, filtrage en symétrie, magnétisme de couche mince, alliage Heusler, système demi-métallique, polarisation tunnel Spintronics with alternative materials: full Heusler alloys and diluted ferromagnetic oxides The polarization of the spin current in a spintronic device is at the origin of magneto-resistive effects that define its functional properties. Typically, in order to spin-polarize a current of electrons two alternatives are used: the electron current crosses either a ferromagnetic metal or a magnetic oxide barrier. Within this thesis, we addressed both alternatives. In a first step, layers of diluted magnetic oxide type TiO 2 doped with cobalt were prepared by sputtering . Their structural, morphological and magnetic properties were studied to optimize their potential for integration into a complex spin filter type structure. In agreement to reports in literature, the results of our studies emphasize the specific problems related to accurate interpretation and control of magnetism in doped oxide systems. In a second step, we focused our efforts on the elaboration and the study of single-crystal magnetic tunnel junction based on the Co 2 FeAl full-Heusler alloy and the MgO(001) tunnel barrier. From a theoretical point of view, the Heusler alloys are expected to be half-metallic. This leads to a theoretical spin polarization of 100%. Following a parallel crystallographic and magnetic study of thin Co 2 FeAl alloy films, we demonstrated a direct correlation between structural and magnetic anisotropies. Using these layers as magnetic electrodes, des couches d'oxyde magnétique dilué de type TiO 2 dopé avec du cobalt ontétéélaborées ontétéontétéélaborées par pulvérisation cathodique. Leurs propriétés structurales, morphologiques et magnétiques ontétéétudiéesontétéontétéétudiées afin d'optimiser leur potentiel d'intégration dans une structure complexe de type filtrèfiltrè a spin this thesis includes studies of analytical, numerical and ab-initio modeling of the magnetic and electronic properties as well as for the spin polarized transport in the studied systems and devices. Key-words: Spin polarized tunnel effect, epitaxial magnetic tunnel junction, spin filter, symmetry filtering, thin film magnetism, Heusler alloy, half-metal system