Magnetization dynamics and magnetotransport in epitaxial nanostructures

The latest magnetoresistive results reported for electrochemically-defined nanocontacts between Ni wires are still quite controversial (Ninth Joint MMM Intermag Conference). We have used e-beam lithography applied to epitaxial Ni films to fabricate nanobridges in more controlled geometry than that of electrochemical deposition. Our studies are important for the understanding of suitable production procedures for Ni nanocontacts. The idea behind our scheme is that epitaxial ferromagnetic thin films exhibit rich magnetic anisotropy and large coercivities at room temperature, associated with only few defects in the crystal lattice. They also exhibit higher anisotropy than polycrystalline films and domain walls with narrower widths are expected. Thus, we speculate that this type of structure would favor ballistic magnetoresistance and possibly domain-wall trapping provided that there is a small enough constriction as predicted by Bruno [Phys. Rev. Lett. 83, 2425 (1999)].