Regensburg 2010 – scientific programme
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MA: Fachverband Magnetismus
MA 17: Spin Dynamics / Spin Torque II
MA 17.12: Talk
Wednesday, March 24, 2010, 17:30–17:45, H10
Experimental Proof for the Vortex-Antivortex Mediated Vortex Core Reversal — •Hermann Stoll1, Arne Vansteenkiste2, Bartel Van Waeyenberge2, Markus Weigand1, Michael Curcic1, Matthias Kammerer1, Matthias Noske1, Georg Woltersdorf3, Kang Wei Chou4, Tolek Tyliszczak4, Christian H. Back3, and Gisela Schütz1 — 1MPI für Metallforschung, Stuttgart — 2Ghent University, Belgium — 3Universität Regensburg — 4Advanced Light Source, LBNL, Berkeley, CA, USA
The reversal of the vortex core polarization via excitation of vortex gyration was discovered experimentally by time-resolved X-ray microscopy [1]. A model was suggested based on dynamic vortex-antivortex (VA) creation and annihilation [1]. Meanwhile this model is generally accepted for vortex core switching. However, in all experiments so far the vortex core polarization was only determined 'before' and 'after' the vortex core reversal and the evidence for the VA model is only indirect, by comparing the experimental parameters with micromagnetic simulations. No direct support for the VA model has been given so far. We present experimental data supporting the VA model directly. Time-resolved imaging of the out-of-plane vortex core magnetization has given a direct proof for the initial step, the deformation of the vortex core [2]. A region with opposite magnetization becomes visible at sufficiently high excitation power when the vortex is gyrating fast and its velocity is approaching the critical velocity.
[1] Van Waeyenberge et al., Nature 444 (2006) 461-464
[2] Vansteenkiste et al., Nature Physics 5 (2009) 332-334