Perpendicular giant magnetoresistance of electrodeposited Co∕Cu-multilayered nanowires in porous alumina templates

The giant magnetoresistance (GMR) of multilayered Co∕Cu nanowires potentiostatically electrodeposited inside the pores of an anodized alumina template was studied in the current perpendicular to the plane (CPP) geometry. The maximum magnetoresistance change of 13.5% was observed for Co(8nm)∕Cu(10nm) nanowires at room temperature. The interfacial roughness and/or an intermixing between Co and Cu layers were varied by changing the Cu deposition potential. However, the CPP-GMR value only slightly decreases as the Cu deposition potential increases to the positive value. This indicates that the interfacial roughness and/or intermixing are not a crucial factor in determining the CPP-GMR value of the Co∕Cu nanowires, which is argued to be due to the uncoupled magnetic layers. The x-ray diffraction shows that Co∕Cu nanowires with 300nm diameter have a face-centered-cubic structure with a strong (111) texture along the wire axes; their magnetic easy axes are perpendicular to the wire axes as determined from the CPP-GMR curve. The effects of the interface roughness and/or an intermixing between Co and Cu layers and their thickness variation on the CPP-GMR are discussed.