Arrays of cobalt (Co) and cobalt-silver (Co-Ag) nanowires have been prepared by electrodeposition using polycarbonate membranes as templates. Scanning electron microscopy characterization revealed a parallel growth of both types of nanowires with constant length. X-ray and electron diffraction patterns showed that cobalt nanowires were grown with hep (hexagonal close-packed) structures, but different preferred orientations were obtained depending on the diameter: (110), (100), and (002) directions for nanowireswith diameters 200, 100, and 50 nm, respectively. The structural differences were reflected on the magnetic response of the nanowires. On the other hand, the structural characterization of Co-Ag nanowires revealed the hcp and fcc (face-centered cubic) structure for cobalt and silver, respectively. The heterogeneous nature of the Co-Ag nanowires was evidenced by transmission electron microscopy. Giant magnetoresistance values as high as 0.5% were measured at room temperature.
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