Optimizing preparation conditions and characterizing for CoxPt1-x alloy cylindrical nanowires fabricated by electrodeposition on nanoporous polycarbonate membranes

Abstract

This study investigated the influence of the preparation conditions on the Co composition, crystal structure, and magnetic and electric conduction properties of cylindrical CoxPt1-x alloy nanowires having 0.08 ≤ x ≤ 0.90, which were electrodeposited on nanoporous templates. When prepared with an optimal concentration ratio of Co and Pt aqueous solutions and electrodeposition potentials, highly oriented crystal structures of fcc Co-Pt (111) was obtained in CoxPt1-x nanowires (0.58 ≤ x ≤ 0.80). Nanowires with (111)-oriented fcc Co-Pt crystals exhibited average lengths and diameters of 5.8–10.8 μm and 130 nm, respectively, and showed an easy axis of magnetocrystalline anisotropy in the longitudinal direction of the nanowire. These results indicate a direct correlation between the crystal structure and magnetic properties. The concentration ratio of Co and Pt in the electrolytes and the electrodeposition potentials for fabricating CoxPt1-x alloy nanowires using the diluted Co composition (0.08 ≤ x ≤ 0.25) were determined. These nanowires were polycrystalline and had a small saturation magnetization. Furthermore, the anisotropic magnetoresistance (AMR) for a single CoxPt1-x nanowire was measured to estimate the domain wall (DW) width in the single CoxPt1-x nanowire. The value of the magnetoresistance (MR) ratio for the single nanowire (0.58 ≤ x ≤ 0.80) with highly (111)-oriented fcc Co-Pt crystal was 0.082–0.23 %, and the estimated value of DW width was 17–25 nm. These findings provide valuable information for constructing three-dimensional magnetic memory devices.