Abstract Nucleation and growth mechanisms of Co and Co-Pt magnetic nanowires (NWs), electrodeposited within anodic alumina templates with pore diameters of 55 nm, are described. Pure Co NWs and Co-Pt bimetallic NWs were electrodeposited at overpotentials of -0.6 and -0.9 V vs. Ag/AgCl. The electrodeposition process occurs predominantly under diffusional control, with the current decreasing monotonically over time. Experimental current-time curves for cobalt are modeled using a diffusional approach adapted for bimetallic phases by considering successive stages of pore filling. In anodic aluminum oxide membranes with small pore diameters, a linear diffusion zone ahead of the growing NW surface allows application of a modified Cottrell equation. Models based on recessed microelectrode behavior are proposed, accounting for overlapping diffusion zones at the porous mouth and hydrogen evolution contributions. The proposed electrocrystallization mechanisms align with NW morphology observed in scanning electron microscopy images. Structural characterization reveals a textured hcp lattice in pure Co NWs at both potentials, while alloyed NWs show a predominant fcc Pt(Co) solid solution at -0.6 V and a minor hcp phase at -0.9 V. Magnetic characterization at room temperature indicates deposition potential does not significantly affect the effective magnetic anisotropy of Co NWs, but alloyed NWs exhibit noticeable differences.
Arce et al. (Mon,) studied this question.