Structure and magnetic properties of electrodeposited cobalt nanowires

TLDR

The study investigates the structural and magnetic properties of cobalt nanowires (100–400 nm diameter, ≤6 µm length) fabricated by electrodeposition in polycarbonate membranes. The authors explain the observed magnetic behavior with a simple magnetostatic model incorporating dipolar interactions, demagnetizing fields, and cobalt’s magnetocrystalline anisotropy. Diffraction confirms hcp Co with (0001) texture perpendicular to the wire axis, and room‑temperature magnetometry shows the easy axis shifts from along the wire for short wires to perpendicular for long wires, with a crossover at intermediate lengths.

Abstract

This work focuses on the structural and magnetic characterization of arrays of cobalt nanowires, with diameters in the range 100–400 nm and lengths of L⩽6 μm, produced by electrodeposition in polycarbonate membrane pores. Diffraction patterns of Co nanowires indicate that Co is stabilized in the hcp structure with a preferential (0001) texture oriented close to the perpendicular direction of the wires axes. Magnetic measurements at room temperature reveal that magnetization undergoes a change in the easy axis as the length of the wires increases. Clearly, the easy axis of the shortest wires is oriented along the axis of the wire. In the case of the longest wires, a crossover of the easy axis is observed, from the perpendicular to the parallel direction to the wire for the shortest. This magnetic behavior is explained through a simple magnetostatic model, which takes into account the dipolar interactions among wires, the demagnetizing field, and the magnetocrystalline anisotropy of Co.