Dresden 2009 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 13: Poster Ia: Electron Theory (1); Magnetic Imaging (2,3); Thin Films (4-25); MSMA (26-33); Magn. Semiconductors (34-42); Magn. Half Metals and Oxides (43-60)

MA 13.4: Poster

Dienstag, 24. März 2009, 10:15–13:00, P1A

Non-Linear Magnetic Vortex Gyration — •André Drews¹, Benjamin Krüger², Stellan Bohlens², Markus Bolte¹, and Guido Meier¹ — ¹Institut für Angewandte Physik und Zentrum für Miktrostrukturforschung, Universität Hamburg, Hamburg, Germany — ²I. Institut für Theoretische Physik, Universität Hamburg, Hamburg, Germany

Magnetic vortices occur in disk- or square-shaped samples of a few hundred nanometers in soft magnetic materials. When applying an external current the vortex core gyrates around its equilibrium position. For small current amplitudes the trajectory of the gyration can be described analytically by a harmonic oscillator [1,2], for larger amplitudes the trajectory becomes nonlinear [3]. In this work the nonlinear motion of vortex cores in square-shaped samples is investigated. The nonlinear analytical equation of motion of the vortex core is solved numerically by a Runge-Kutta method. The analytical results match well with the results from micromagnetic simulations. The amplitude and frequency of the gyration in dependence on the excitation amplitude are investigated, and it is shown that with increasing excitation amplitude the nonlinearities and the blue shift of the resonance frequency increase. For varying lengths and thicknesses of permalloy squares the limits of linear vortex gyration are determined.

[1] B. Krüger et al., Phys. Rev. B. 76, 224426 (2007).

[2] A. Drews et al., Phys. Rev. B. 77, 094413 (2008).

[3] K.-S. Lee and S.-K. Kim, Appl. Phys. Lett. 91, 132511 (2007).