Electrochemical synthesis and magnetoresistance properties of Ni, Co and Co/Cu nanowires in a nanoporous anodic oxide layer on metallic aluminium

The layer thickness of anodized aluminium oxide was controlled by anodization time and voltage to obtain templates with the desired pore-length. The barrier layer at the pore bottom of anodized aluminium templates was chemically etched to make good electrical contacts for nanowires electrodeposited in the pores thus formed on metallic aluminium substrates. Ni and Co homogeneous nanowires and Co/Cu multilayered nanowires were fabricated in the anodized aluminium templates using the electrodeposition technique and also in ion-track etched polycarbonate templates for comparison. The thicknesses of the Cu- and Co-rich layers were controlled in the range of 5 to 15 nm by varying each deposition time. Ni and Co homogeneous nanowires in aluminium templates showed typical anisotropic magnetoresistance (AMR) of around 1.0%. Co/Cu multilayered nanowires in aluminium templates reached a giant magnetoresistance (GMR) of 20% in current perpendicular to the plane geometry.