Tailoring structural and magnetic properties of NiCu nanowires by electrodeposition

In this work, we investigated the tailoring of structural and magnetic properties of NiCu nanowires through electrodeposition. Continuous (S1) and composition-modulated (S2) wires were fabricated by electrodeposition using porous alumina membranes as a template. Morphological characterization revealed that the total length of the wires was 8 ± 3 µm in both S1 and S2. For the composition-modulated wires, the length of the segments with the lowest and highest Cu concentrations was 1.2 ± 0.4 µm and 226 ± 65 nm, respectively. Mapping by energy dispersive spectroscopy (EDS) revealed that the concentration of copper and nickel varied along the length of the composition-modulated nanowires, while the continuous nanowires contained a relatively constant concentration of both metals. It is demonstrated that the change in Cu concentration along the wire modifies the lattice parameter, average crystallite size (D) and lattice strain (ε) of Ni. This result is pivotal for understanding the magnetic properties of the wires, as nickel is primarily responsible for the magnetic behavior of the wires. From the ferromagnetic resonance (FMR) results, the linewidth and resonance field values for samples S1 and S2 were determined. It was demonstrated that the greater deformation in the nickel lattice in NiCu nanowires increases the angular dependence of the resonance field. Furthermore, the smaller nickel crystallite size was shown to increase spin dispersion and magnetic damping, leading to complex behavior in FMR responses. Finally, it was demonstrated how Cu can influence the magnetic properties such as coercivity (H_C) and squareness (M_R/M_S) of the wires. Overall, this work contributes to understanding the tailoring of structural and magnetic properties of NiCu nanowires through electrodeposition.