Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 16: Micro- and Nanostructured Magnetic Materials II

MA 16.8: Vortrag

Mittwoch, 24. März 2010, 12:00–12:15, H23

Domain walls in bent nanowires — •André Kobs, Sebastian Hankemeier, Robert Frömter, and Hans Peter Oepen — Institut für Angewandte Physik, Universität Hamburg, Jungiusstr. 11, 20355 Hamburg, Germany

We have investigated the magnetic fine structure in remanence and the appearance of domain walls in bent nanowires depending on their geometrical properties by means of scanning electron microscopy with polarization analysis (SEMPA). The wires were carved from 18 nm thick soft-magnetic Co₃₉Fe₅₄Si₇ film via Focused Ion Beam (FIB) milling. By gradually decreasing the angle of the bend we find the transition from vortex wall to transverse wall via the so called asymmetric transverse wall. For the vortex walls, the vortex core is not exactly aligned with the mirror axis of the wire, but is slightly shifted into one of the two arms of the wire. The direction of the magnetic field that is used to seed the domain wall determines which of the energetically degenerated vortex wall states occur. More important, the chirality is linked to the location of the vortex wall and is therefore also experimentally accessible. Micromagnetic simulations verify these results and show in addition that the polarity can be tuned on purpose by applying a moderate out of plane field during vortex core nucleation. The ability to control the chirality and the polarity is a necessary prerequisite for new storage concepts based on vortex walls in combination with current induced domain wall movement, like in the racetrack memory device.