Regensburg 2010 – scientific programme

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MA: Fachverband Magnetismus

MA 20: Micromagnetism / Computational Magnetics

MA 20.5: Talk

Wednesday, March 24, 2010, 18:00–18:15, H22

Micromagnetic study of field-driven domain wall dynamics in Permalloy nanotubes — •Christian Andreas, Ming Yan, Attila Kákay, and Riccardo Hertel — Institut für Festkörperforschung, Elektronische Eigenschaften, Forschungszentrum Jülich GmbH

At sufficiently large propagation velocity, magnetic domain walls (DWs) in thin strips reach the Walker limit^[1], a dynamic micromagnetic instability characterized by complex domain wall transformations and a drastic reduction of the DW speed. Using our hybrid FEM/BEM micromagnetic code, we found that DWs in nanotubes are much more stable against such transformations than DWs in thin strips. We studied in detail the field-driven motion of vortex DWs^[2] in Permalloy nanotubes with outer diameter of 60 nm and various inner diameters. In the case of nanotubes, the breakdown process involves the nucleation of a vortex-antivortex pair, while in thin strips a single (anti-)vortex is nucleated at the lateral boundary. These differences are due to topological reasons and also lead to different values of the critical field, since the threshold for pair creation is higher than for the nucleation of a single (anti-)vortex. In conclusion we find that DWs in nanotubes can propagate much faster than in thin strips. The possibility to fabricate such magnetic nanotubes^[3] should allow for the experimental verification of the predicted fast DW motion.
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R. Hertel et al., J. Magn. Magn. Mater. 278 291 (2004)
K. Nielsch et al., J. Appl. Phys. 98 034318 (2005)