Magnetization processes in nickel and cobalt electrodeposited nanowires

We report on the magnetic properties of arrays of submicronic (35 nm-500 nm) Ni and Co wires fabricated by electrodeposition into the cylindrical pores of track-etched polymer membranes. This work reveals intrinsic differences between the magnetization reversal mechanisms taking place in these two systems. For Ni, the crystal anisotropy is small compared to the shape anisotropy and the magnetization lies along the wire axis. In contrast, the strong crystal anisotropy of Co and the orientation of the crystal easy axis (nearly perpendicular to the wire axis), allows for the appearance of a multidomain magnetization configuration, each domain being oriented partially along the normal to the wire axis. Experimental evidence for the existence of this multidomain configuration has been obtained from resistivity and magnetization measurements. Large scale micromagnetic calculations for Co and Ni wires with high aspect ratios corroborate the strong influence of the crystal anisotropy on the overall properties of Co wires and provide an accurate microscopic description of the nucleation fields and the magnetization reversal mechanism for Ni wires.