Regensburg 2007 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 15: Poster:ThinFilms(1-33),Transp.(34-49),ExchBias(50-56),
Spindynamics(57-70),Micro-nanostr.Mat.(71-82),
Particles/Clust.(83-88), Mag.Imag./Surface(89-96),
Spinelectronics(97-109), Theory/Micromag.(110-116),
Spinstruct/Phasetr.(117-128),Magn.Mat.(129-139),
Aniso.+Measuring(140-145), MolMag.(146-152),
MSMA(153-156)

MA 15.116: Poster

Dienstag, 27. März 2007, 15:00–19:00, Poster A

Current-induced magnetic vortex core reversal in a permalloy nanodisk — •Yaowen Liu, R. Hertel, and Claus M. Schneider — Institut für Festkörperforschung IFF-9 "Elektronische Eigenschaften", Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany

Magnetic vortex structures in ferromagnetic thin-film elements contain a nanometric core magnetized perpendicular to the film plane [1]. It has recently been demonstrated that a vortex core can be switched by short, resonant magnetic field pulses applied in the film plane [2]. In this work, we use micromagnetic finite-element simulations to demonstrate that vortex cores can also be switched by in-plane sub-ns electric current pulses. The vortex core of a permalloy nanodisk of 200 nm size and 20 nm thickness can be switched, e.g., by a 200 ps polarized current pulse with a peak value of 5×10⁸ A/cm². In the simulations, both the spin transfer torque (adiabatic) term and the force (non-adiabatic) term due to the current have been considered. The simulations show that the core switching process is mediated by a rapid vortex-antivortex pair creation and annihilation mechanism [3]. For stronger current pulses, multiple core reversals are observed. By changing the strength of the current pulse, the number of the reversal times can be controlled.

[1] Shinjo et al. Science 289, 930 (2000).

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

[3] R. Hertel and C.M. Schneider, PRL 97, 177202 (2006).