Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 19: Micro Magnetism / Computational Magnetism
MA 19.8: Vortrag
Mittwoch, 25. März 2009, 12:00–12:15, HSZ 403
Stimulated vortex-antivortex pair creation in ferromagnetic thin film elements — •Sebastian Gliga, Riccardo Hertel, and Claus M. Schneider — Institut für Festkörperforschung (IFF-9), Forschungszentrum Jülich, Jülich, Germany
Charged pair production from the vacuum is a ubiquitous phenomenon in quantum mechanics, and can be triggered by high-intensity focused laser pulses. Using micromagnetic simulations, we demonstrate that the production of vortex-antivortex pairs can equally be stimulated by applying a strong local field in the direction opposite to the magnetization, even in samples too small to permanently sustain a vortex-antivortex structure. The dynamics of such pairs has recently attracted increased attention: they play a crucial role in the vortex core reversal process [1] and it has also been found that they could annihilate in zero field [2], interact with each other altering their dynamic behavior [3] or rotate under the influence of a DC spin-polarized current [4]. As an example of pair creation, we show that a short 1.2 Tesla field pulse over a small region (20 nm3) in a sub-micron sized Permalloy disk of 20 nm thickness leads to the temporary creation of a vortex-antivortex pair. This pair production is consistent with the local increase of the energy density due to the applied field. These energy densities are compared to the ones found during the vortex core switch process.
[1] R. Hertel et al., Phys. Rev. Lett. 98, 117201 (2007); [2] R. Hertel and C. M. Schneider, Phys. Rev. Lett. 97, 177202 (2006); [3] K. Kuepper et al., Phys. Rev. Lett. 99, 167202 (2007); [4] G. Finocchio et al., Phys. Rev. B 78, 174408 (2008)