  The deliberate control over the spatial arrangement of nanostructures is the
desired goal for many applications as e.g. in data storage, plasmonics or
sensor arrays. Here we present a novel method to assist the self-assembly
process of magnetic nanoparticles. The method makes use of nanostructured
aluminum templates obtained after anodization of aluminum disks and the
subsequent growth and removal of the newly formed alumina layer, resulting in a
regular honeycomb type array of hexagonally shaped valleys. The iron oxide
nanoparticles, 20 nm in diameter, are spin coated onto the nanostructured
templates. Depending on the size, each hexagon site can host up to 30
nanoparticles. These nanoparticles form clusters of different arrangements
within the valleys, such as collars, chains, and hexagonally closed islands.
Ultimately, it is possible to isolate individual nanoparticles. The strengths
of magnetic interaction between particles in a cluster is probed using the
memory effect known from the coupled state in superspin glass systems.
