Regensburg 2007 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 7: Micromagnetism/Computational Magnetics

MA 7.4: Vortrag

Montag, 26. März 2007, 17:45–18:00, H10

Switching magnetic vortices on the picosecond timescale — Riccardo Hertel, •Sebastian Gliga, and Claus M. Schneider — Institut für Festkörperforschung IFF-9 “Elektronische Eigenschaften”, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany

Magnetic vortices are naturally occurring structures in confined-geometry ferromagnetic materials: regions where the magnetization curls around a perpendicularly magnetized core. Highly stable, the core has until now been assumed to behave like a rigid structure. Only very recently has it been shown that the core could easily be switched by applying an in-plane magnetic pulse [1].

In this study, we present the dynamics of vortex core reversal using three-dimensional micromagnetic simulations based on finite-elements. The simulations show that a single suitable in-plane magnetic pulse of intermediate strength (ca. 70 mT) can be used to reverse the orientation of a vortex core. We found that this process is mediated by the creation and annihilation of a vortex-antivortex pair in the sample. We have systematically studied the influence of the field pulse strength and duration and found that it is possible to trigger the core reversal with ultrafast pulses (as short as 5 ps). The simulations predict that for very strong pulses, the core switches multiple times.

We find that the magnetization dynamics is driven by the exchange field, which allows the magnetization reversal process to unfold on the picosecond time scale, making it faster than any field-driven magnetization reversal process previously known from micromagnetic theory.

[1] B. Van Waeyenberge et al., Nature 444, 461 (2006)