Retardation of oxidation in Co nanocolumns: Scanning tunneling microscopy study

Abstract
The oxidation of Co nanocolumns grown by the glancing angle deposition technique was studied ex situ using scanning tunneling microscopy and spectroscopy. The normalized conductance (dI/dV)/(I/V) of a single nanocolumn shows a nonoxidized Co peak at about −0.7 eV corresponding to the 3d valence electrons which was absent in the conventional film. It is argued that a retardation of the oxidation occurred in the Co nanocolumn due to the lack of grain boundaries in the isolated nanocolumns.