Regensburg 2007 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 7: Micromagnetism/Computational Magnetics
MA 7.2: Vortrag
Montag, 26. März 2007, 17:15–17:30, H10
Current-induced high-frequency normal modes in single-crystalline Fe nanodisks — •A. Kakay, R. Hertel, and C. M. Schneider — Institut für Festkörperforschung IFF-9 "Elektronische Eigenschaften", Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
The magnetization dynamics in a single-crystalline Fe nanodisk (diameter: 150 nm, thickness: 4 nm) driven by a spin-polarized current flowing perpendicular to the plane has been studied by means of micromagnetic simulations. The micromagnetic simulations have been performed with a finite-element algorithm based on the Landau-Lifshitz-Gilbert equation including Slonczewski’s torque term. The magnetic excitations are induced by a spin-polarized current. At current densities between 4-6×1011A/m2, two pronounced peaks can be observed in the Fourier spectra. A spatial Fourier filtering shows that the lowest frequency peak (12.2 GHz) arises from a magnetic mode localized at opposite sides of the nanodisk. The main peak at 15.7 GHz represents a macrospin oscillation. In addition, well-defined and more complicated normal modes are observed in a frequency range around 22 GHz. Our simulations show that spin-polarized currents can induce stationary, non-uniform high-frequency normal modes, similar with those reported on the magnetization dynamics created by external field pulses. The occurrence of these normal modes emphasizes the need for a full-scale micromagnetic approach. The influence of the Oersted field (created by the current flowing through the sample) on the high-frequency normal modes will also be discussed.