Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

MA: Magnetismus

MA 32: Mikro- und nanostrukturierte magn. Materialien II

MA 32.3: Vortrag

Mittwoch, 9. März 2005, 11:30–11:45, TU H1028

Magnetic Properties of Cobalt/Polymer Composite Nanotubes — •Kornelius Nielsch¹, Fernando J. Castaño², Sven Matthias¹, Woo Lee¹, Ramkumar Krishnan², and Caroline A. Ross² — ¹Max Planck Institute of Microstructure Physics, Halle, Germany — ²Massachusetts Institute of Technology, Cambridge, MA, USA

In the present work we report on a novel approach for the fabrication of ferromagnetic nanotubes and present results concerning the magnetic properties of Co nanotubes. The pores surfaces in porous alumina membranes patterned by imprint lithography and macroporous silicon membranes are wetted with a polystyrene layer containing a metallo-organic precursor with a thickness of 40 to 70 nm. During an annealing process at 180 C for 24 h, a cobalt thin-film forms at the oxide pore-wall/polymer interface. The decomposition of the precursor leads to the formation of thin-walled magnetic tubes with diameters of 160 to 520 nm and wall thicknesses of 1 to 5 nm. Magnetic measurements at room temperature and 5 K show that the tubes have a lower saturation field parallel to their axes, while the in-plane direction is a harder axis. The magnetic properties on varying the wall thickness and diameter of the nanotubes will be discussed. This synthesis method is not limited to Co. We have also precipitated metallic Fe and Ni nanotubes based on polymer wetting of porous templates.