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Magnetic nanostructures prepared by electrochemical and replica/antireplica processes
M. Vázquez Instituto de Ciencia de Materiales, 28049 Madrid, Spain E-mail: mvazquez@icmm.csic.es |
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A variety of magnetic wire arrays can be then prepared keeping the order imposed by the NAA: single metallic wires (i.e., Co and FeNi), multilayer metallic wires (i.e., Co/Cu), oxide wires (i.e., diluted magnetic semiconductor as Mn doped ZnO). Very recently, radial arrays of nanowires have been obtained by anodization of micrometric aluminium wire.
NAA are employed as templates for the preparation of magnetic nanostructures through replica/antireplica processes. Nanohole arrays in metallic membranes are prepared through the following processes: sputtering of a nanometric layer (typically Au), pressing filling of pores with polymer (typically PMMA), chemical removing the precursor NAA and aluminium, and final electroplating using the Au layer as an electrode. The final metallic membrane exhibit magnetic behaviour (i.e., Ni) or no (i.e., Au) depending on the final electroplated metal.
Nanostructured magnetic polymers can be obtained using aluminium as template after first anodization and subsequent etching of alumina. In this case, magnetic nanoparticles (typically CoNi and ferrite) are firstly embedded in the polymer. Magnetic coatings can be also prepared by suitable sputtering onto non-magnetic polymer giving rise to nanostructured coating (i.e., Co).
The detailed analysis of the magnetic behaviour of the above mentioned systems has been performed by vibrating sample magnetometry under in-plane and out-of-plane applied magnetic field. Results are combined with the information of local magnetic state of individual nanobjects by magnetic force microscopy.