Dresden 2011 – scientific programme
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MA: Fachverband Magnetismus
MA 10: Magnetization Dynamics I
MA 10.3: Talk
Monday, March 14, 2011, 15:15–15:30, HSZ 403
Dynamics of field-driven vortex walls in GMR nanostripes under the influence of transverse fields — Björn Burkhardt, •Sascha Glathe, and Roland Mattheis — IPHT Jena e.V., Albert-Einstein-Str. 9, 07745 Jena
The character of DW movement in nanostripes (l>>w>>d)is mainly determined by the thickness and width of a nanostripe. Two different types of domain walls, vortex (VW) or transverse walls (TW), can occur in these nanostripes. We have charcterized wide nanostripes (w = 500nm) with a thickness of 20nm. In these dimensions VW are energetically preferred. However, for fields above a critical field Hcr (well below the Walker field Hw) the VW is converted to a TW.
The dependence of DW velocity on the applied field was measured using the giant GMR effect between a sense layer (NiFe) and a reference layer (CoFe - part of an AAF/AF-combination). We applied field pulses to investigate the DW motion independently of the nucleation field. Short current pulses in a coplanar wave guide crossing the GMR nanostripe were used to generate the magnetic field. The parameters of field driven DW motion e.g. critical field, Walker field and mobilities in the different regions were determined. Especially the VW characteristics below Hw are rarely treated, yet. The precession period of the domain wall above Hw was estimated by means of measurements with different pulse length.
Furthermore we will show the influence of an in-plane transverse field on the DW dynamics in wide nanostripes by simulations and experimental results.