Study On The Electrochemical Preparation And Properties Of Co/Cu Multilayered Nanowires

The magnetic Co nanowire arrays, Cu nanowire arrays, Co nanotube arrays, Co nanoparticle arrays and Co/Cu multilayered nanowire arrays were prepared by electrochemical deposition into the nanoporous anodic alumina oxide (AAO) templates. The morphology, structure and magnetic properties of the nanowires were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and Giant-Magnetoresistance (GMR) properties tester (self-assembled), respectively.The anodic aluminum oxide membranes were prepared by two-step oxidation in the solution of oxalic acid, and stripped from the aluminum substrate adopting strip against electricity technique. The oxide barrier layer was chemically dissolved from bottom side of the film in phosphoric acid.Ordered Co nanowire arrays, Cu nanowire arrays, Co nanotube arrays and Co nanoparticle arrays were prepared by electrochemical deposition into the nanoporous anodic alumina oxide (AAO) templates using single bath method. XRD showed that the Co nanowires arrays were were in fcc structure, the Cu nanowire arrays were in hcp structure. The results indicated that the nanowires in an array were very regular, with an aspect ration controllably. The hysteresis loops showed that the Co nanowire arrays had excellent perpendicular magnetic anisotropy with their easy magnetization axis parallel to nanowire arrays. When the magnetic field was perpendicular to the membranes, the coercivity of Co nanowire arrays (diameter=80nm) was 1010Oe.Which is larger than coercivity (as high as 380Oe) when the magnetic field was parallel to the membranes. Those of Co nanowire arrays (diameter=120nm) and Co nanotube arrays (diameter=120nm) were 900Oe, 330Oe and 460Oe, 126Oe, respectively. The nanoparticle with two diameters (120nm, 80nm) were fabricated successfully by electrodeposition into the pores of a porous anodic aluminum oxide (AAO)Highly ordered Co/Cu multilayer nanowire arrays with different layer thickness (10nm, 25nm, 100nm, 150nm) were fabricated successfully by electrodeposition into the pores of a porous anodic aluminum oxide (AAO) using single bath method. the nanowire arrays were regularly arranged. All the thickness of single layer of Co/Cu multilayer nanowires are same. The Co layers and Cu layers of multilayer nanowires were in hcp and fcc structures respectively. The crystal direction of Co layers of Co/Cu nanowires is not obviously affected by Cu layer. The magnetic coercivity of Co/Cu multilayer nanowire arrays with the diameter of 80 nm is larger than that of 120nm. When the layer thickness of Co/Cu multilayer nanowire arrays increased the magnetic coercivity decreased. When the layer thickness of Co/Cu multilayer nanowire arrays is 25nm, the GMR is max. The GMR of Co/Cu multilayer nanowire arrays with the diameter of 80 nm is larger than that of 120nm. The SDL of the Co and Cu layers of Co/Cu multilayer nanowire arrays was less than 100nm.