The oxidation of metal-capped Co cluster films under ambient conditions

• Published in: Nanotechnology Vol. 20; no. 8; p. 085710
• Main Authors: De Toro, J A, Andrés, J P, González, J A, Muñiz, P, Riveiro, J M
• Format: Journal Article
• Language: English
• Published: England 25-02-2009
• Subjects: Cobalt - chemistry; Copper - chemistry; Crystallization - methods; Macromolecular Substances - chemistry; Materials Testing; Membranes, Artificial; Molecular Conformation; Nanostructures - chemistry; Nanostructures - ultrastructure; Nanotechnology - methods; Oxidation-Reduction; Particle Size; Surface Properties; Titanium - chemistry
• ISSN: 1361-6528
• DOI: 10.1088/0957-4484/20/8/085710

We report on the unexpected deterioration under ambient conditions of films of Co clusters capped with relatively thick (>100 nm) Cu (or Ti) layers deposited by either thermal evaporation or by radiofrequency sputtering. The magnetic character of the clusters, prepared by gas-phase condensation, allows monitoring the oxidation of the samples through the decay of the saturation magnetization, which takes place on a timescale of days. By contrast, diluted (<10 at.%) cluster-assembled granular Co:Cu films, prepared by co-deposition of the Co clusters with a Cu vapour, are perfectly stable under ambient conditions. We tentatively explain the oxidation of the cluster films as stemming from their very high porosity.