Nanostructured Co film on ordered polymer nanohills: a base for novel magnetic nanostructures

The preparation of a nanostructured polymer (poly(methyl methacrylate)--PMMA) replicating the order of an anodized aluminium (Al) template is first described. Nanohills at the PMMA surface are structured following the ordering of the template with tailored lattice parameter and hexagonal symmetry. A nanostructured Co magnetic film is then deposited by sputtering onto the polymer surface so keeping the high ordering induced by the precursor template. The magnetic properties depend on the polymer periodicity as well as on the sputtering conditions. In particular, single-domain or multidomain structures have been identified inside every Co/polymer hill depending on the lattice parameter. Moreover, an intrinsic distribution of the magnetic anisotropy can be deduced from the hysteresis loops.