Nanoscale characterization of CoPt/Pt multilayer nanowires

Abstract

CoPt/Pt multilayer nanowires have been successfully fabricated by a dc electrodeposition technique into anodic aluminium oxide (AAO) templates, and their chemistry and crystal structure characterized at the nanoscale. It was found that each individual multilayered nanowire had a regular periodic structure like bamboo. However, the periodicity of diverse nanowires from the same specimen varied in magnitude. The Pt layers grew to the full width of the AAO template. However, the cobalt-rich layers in each nanowire did not fully fill the template pores during growth, resulting in a repeatably oscillating nanowire diameter. The chemical composition of multilayer nanowires was measured to be (Co72Pt28/Pt)n. Both the Co72Pt28 and Pt layers were polycrystalline, consisting of fcc nanocrystals <5 nm in size. The variable nanowire periodicity and wire diameter will result in variable mechanical strength, resistance and GMR effect.