This thesis deals with the study of the influence of the nanostructuration of the Cu-Co system on its magnetic and magnetoresistive properties. As a first step, the granular Cu 80 Co 20 alloy was obtained as powders, thin films and nanowires. Powders were produced by mechanical milling. Thin films and nanowires were obtained by electrodeposition. This allowed investigating the influence of both the sample shape and the elaboration technique on the nanostructure and the magnetic and magnetoresistive properties of the samples. In a second step, multilayered Cu/Co nanowires have been prepared by electrodeposition. Experimental protocols for nanoscale analyses by transmission electron microscopy and atom probe tomography were developed. Such analyses have proved essential to allow the understanding and full correlation of magnetic and magnetoresistive properties. Contrary to many published results, which concluded to the formation of solid solutions on the basis of microstructural investigations, the analyses at the nanometric scale by tomographic atom probe and transmission electron microscopy of our granular alloys revealed that no Cu-Co solid solution have been obtained. In addition, the presence of a positive effect of the magnetoresistance under low applied magnetic field was observed, and correlated to the presence of oxides.
