Berlin 2008 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 19: Spin Dynamics / Spin Torque I
MA 19.13: Vortrag
Mittwoch, 27. Februar 2008, 17:15–17:30, EB 301
Harmonic oscillator model for current and field-driven vortices and antivortices — •Benjamin Krüger1, André Drews2, Markus Bolte2, Ulrich Merkt2, Daniela Pfannkuche1, and Guido Meier2 — 11. Institut für Theoretische Physik, Universität Hamburg, 20355 Hamburg, Germany — 2Institut für Angewandte Physik, Universität Hamburg, 20355 Hamburg, Germany
We investigate the gyroscopic motion of current- and field-driven magnetic vortices and antivortices in micro- or nanostructured thin-film elements by analytical calculations and by micromagnetic simulations [1]. Starting from micromagnetic equations of motion we derive an analytical expression for the current- and Oersted-field driven trajectory of the vortex and antivortex. For small harmonic excitations the vortex and antivortex cores perform an elliptical rotation around their equilibrium positions. Our analytical model allows to calculate the amplitude and the phase of the current- and Oersted-field driven gyration. The global phase of the rotation and the ratio between the semi-axes are determined by the frequency and the amplitudes of the field and the spin torque. The accordance between analytical and numerical approaches is very good. Even though the influence of the Oersted field on the trajectories of a vortex or antivortex is small, the phase of the rotation is significantly changed. Thus, the model can give an estimate of the Oersted-field’s contribution in spin-torque experiments.
[1] B. Krüger, A. Drews, M. Bolte, U. Merkt, D. Pfannkuche, and G. Meier, Phys. Rev. B, accepted.