Magnetic interactions in Ni–Cu/Cu superlattice nanowire arrays

Abstract

The remanent magnetization of Ni–Cu/Cu superlattice nanowires was investigated. Arrays of superlattice nanowires were prepared by template deposition through polycarbonate nanoporous membranes using a single electrolyte bath. The thicknesses of the nickel-rich layers (tNi) and copper layers (tCu) were independently controlled by monitoring the current during deposition. The wire diameter was determined by transmission electron microscopy imaging to be 80 nm. A study of the remanent magnetization at 20 K for a range of values of tNi and tCu reveals the existence of magnetic interactions within each array. It is noted that for an array with tNi of 200 Å, the strength of the interactions decreases with increasing tCu, indicating that the interactions are taking place between nickel layers. However the interaction strength appears to reach a minimum level, beyond which an increase in tCu does not correspond to a decrease in the interaction strength observed. A minimum interaction level is also observed for an array with tNi of 50 Å, for all values of tCu investigated.