Preparation and characterization of Ni or Co/Cu multilayer nanowires

Highly ordered nanowires with multilayer structure of Ni/Cu, have been successfully prepared by pulsed chemical electrodeposition into nanoporous templates and the diameter (35 and 200 nm) of wires can be easily controlled by pore size of template. The nanowires have been characterized by transmission electron microscopy (TEM), magnetic force microscopy (MFM), and vibrating sample magnetometer (VSM) and high magnetic perpendicular anisotropy can be achieved by modulating the shape of nanowires. It was found that the coercivity (Hc) and squarness (S: Mr/Ms) of the nanowires are strongly dependent on the diameter and aspect ratio as well as on dipolar coupling between the ferromagnetic segments and the nanowires (aspect ratio: 11.4) can be obtained high perpendicular magnetic anisotropy with Hc: 895 Oe and S: 0.77 of Ni/Cu nanowires. The magnetoresistance ratios along the parallel and perpendicular axes of nanowires are 23.4% and 7.2% respectively. Owing to its high bit density, the structure may be suitable for ultrahigh-density magnetic recording media.