Berlin 2008 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 7: Micro and Nanostructured Magnetic Materials II
MA 7.5: Vortrag
Montag, 25. Februar 2008, 16:15–16:30, EB 301
Nucleation and propagation of transverse and vortex domain walls in nanowires with a thickness gradient — •Oleg Petracic1,3, Hartmut Zabel1, Detlef Görlitz2, Kornelius Nielsch2, Dan Read3, and Russell P. Cowburn3 — 1Institut für Experimentalphysik, Ruhr-Universität Bochum, D-44780 Bochum — 2Institute of Applied Physics and Microstructure Research Center, University of Hamburg, D-20355 Hamburg — 3Physics Department, Imperial College London, London SW7 2AZ, UK
Permalloy nanowires with a thickness gradient along the nanowire axis have been prepared by electron beam lithography and studied using a magneto-optic Kerr effect setup. The nucleation and propagation of either transverse or vortex domain walls is strongly modified by a slope in the thickness. For relatively narrow and thin wires, i.e., width w = 150nm and thickness t=8nm, wires with a slope have a strongly decreased coercive field compared to wires without a slope. However, wider and thicker wires, i.e., w=500...2000nm and t=18nm show a much smaller effect of the slope. We assume that in the sloped region a transverse domain wall nucleates for all wire geometries. For narrow and thin wires the transverse wall is the energetically preferred configuration, while wider and thicker wires show a vortex wall. The initial transverse wall either can propagate through the entire wire or has to transform to a vortex wall, respectively. Micromagnetic simulations confirm our experimental investigations.