AVS 50th International Symposium
    Magnetic Interfaces and Nanostructures Monday Sessions
       Session MI-MoA

Paper MI-MoA7
Magnetization Dynamics and Magneto-transport in Epitaxial Nano-structures

Monday, November 3, 2003, 4:00 pm, Room 316

Session: Magnetic Recording and Magnetoresistive Structures
Presenter: R.A. Lukaszew, University of Toledo
Authors: R.A. Lukaszew, University of Toledo
D. Pearson, University of Toledo
Z. Zhang, University of Toledo
A. Zambano, Michigan State University
Correspondent: Click to Email
Abstract: The latest results on ballistic magneto-resistance (BMR) research have shown surprising ballistic magnetoresistance.@footnote 1@ It has been postulated that the BMR effect arises from non-adiabatic spin scattering across very narrow magnetic domain walls trapped at nano-sized constrictions.@footnote 2@ The reported BMR effect has been observed in nano-contacts electrodeposited between Ni wires. Much of the publish data so far, is still poorly understood. In an attempt to clarify some of the possible processes present in the observed phenomena we applied e-beam lithography to epitaxial Ni films to fabricate nano-bridges with more controlled geometry than the ones made with electrochemical deposition. Epitaxial ferromagnetic thin films exhibit narrow domain walls that may favor ballistic regime provided that the nano-contact is small enough. We have modeled the magnetization reversal in epitaxial films and have established that the unusually high coercive field observed along hard axes is due to a second order type transition prior reversal that induces high density of domain walls at the reversal.@footnote 3@ Thus we expect that a patterned nano-structure with segments parallel to magnetization hard axes will be more likely to experience domain-wall related effects in magneto-transport. Therefore we patterned a similar T geometry to that utilized by Chopra and Garcia.@footnote 1,3@ Our preliminary results indicate that magnetic domains do play a role in the magneto-resistance of these nano-bridges but the order of magnitude of the observed effect is considerably smaller than the reported observations for electrochemically prepared nano-contacts. @FootnoteText@@footnote 1@B. D. Chopra and S. Z. Hua, Phys. Rev. B. 66, 020403(R), 2002. @footnote 2@P. Bruno, Phys. Rev. Lett. 83, 2425 (1999). @footnote 3@Lukaszew, R.A. and Clarke R., unpublished. @footnote 4@N. Garcia, M. Munioz, V. V. Osipov, E. V. Ponizovskaya, G. G. Quian, I.G. Saveliev and Y.-W. Zhao, J. Magn. Magn. Mater. 240, 92 (2002).