Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 7: Spin-Dynamics/ Spin-Torque II
MA 7.11: Vortrag
Montag, 23. März 2009, 18:00–18:15, HSZ 04
electrical switching of the magnetic vortex core polarities in a magnetic circular disk — •June-Seo Kim1, Olivier Boulle1, Steven Verstoep1, Mathias Kläui1, Ulrich Rüdiger1, and Giancarlo Faini2 — 1Fachbereich Physik, Universität Konstanz, Universitätsstr. 10, D-78457 Konstanz, Germany — 2Phynano team, LPN, Route de Nozay, 91460 Marcoussis, France
The recent discovery that a spin-polarized current can induce magnetization dynamics (DW) without an applied magnetic field has created interest in field-induced oscillations of confined spin structures. Especially, a vortex domain wall in a nanowire pinned at an artificial notch can be driven into large amplitude vortex core oscillations by a high frequency alternative current for very low current density (~109 A/m2) [1]. Here, we have observed the resonance of a single magnetic vortex core in an asymmetric Py disk, which allows a better control of the energy landscape felt by the magnetic vortex core. We have measured variations of the dc voltage (homodyne detection) for some particular resonance frequencies that indicate the resonance excitation of the vortex. The shape of the DC voltage vs. frequency curve can be determined by the relative polarities (pointing up and down) of the vortex. Moreover, the eigen-frequencies of the magnetic vortex cores are changed as a function of the amplitudes and angles of applied fields from which the 3D potential landscape can be ascertained. This work is supported by the EU-RTNs SPINSWITCH (MRTN-CT-2006-035327). [1] D. Bedau, M. Kläui et al., Phys. Rev. Lett. 99, 146601 (2007); Phys. Rev. Lett. 101 (in press 2008)