Regensburg 2013 – scientific programme
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MA: Fachverband Magnetismus
MA 49: Magnetization Dynamics III of 3
MA 49.7: Talk
Friday, March 15, 2013, 11:00–11:15, H22
Spin wave mediated sub-100 ps vortex core reversal — •M. Noske1, M. Weigand1, M. Kammerer1, M. Sproll1, G. Dieterle1, A. Gangwar3, B. Van Waeyenberge2, H. Stoll1, G. Woltersdorf3, C. Back3, and G. Schütz1 — 1MPI for Intelligent Systems, Stuttgart — 2Department of Solid State Science, Ghent University, Belgium — 3Department of Physics, Regensburg University
Low field magnetic vortex core (VC) reversal by exciting the sub-GHz vortex gyromode [1] has triggered intensive studies of VC dynamics, also due to its potential for spintronics applications. Recently we could speed up VC switching significantly by exciting magnetostatic azimuthal spin wave modes with rotating multi-GHz ac magnetic field bursts [2,3]. In this contribution we demonstrate VC switching times below 100 ps and unidirectional VC reversal in sub-micron Permalloy discs by excitation with two orthogonal unipolar magnetic field pulses of 50 ps. The magnetization dynamics during VC reversal were imaged by time-resolved scanning transmission X-ray microscopy at the MAXYMUS endstation at BESSY II with time and spatial resolution of 45 ps and 25 nm. Phase diagrams for VC reversal were obtained by varying lengths, amplitudes and the sense of rotation of the pulse sequence revealing a small parameter range for selective VC reversal. All our results are in good agreement with micromagnetic simulations.
[1] B. Van Waeyenberge et al., Nature 444, 461-464 (2006).
[2] M. Kammerer et al., Nature Communications 2, 279 (2011).
[3] M. Kammerer et al., PRB 86, 134426 (2012).