The influence of non centric holes on the magnetization dynamics of Landau structures

Magnetic vortex cores are attracted and can be trapped by artificial defects. If more than one of such defects are created a switching between different vortex core trapped states, which might serve as discrete levels in a multivalent memory device, can be achieved. Up to now a number of studies of circular vortex structures comprising holes has been reported, e. g. [1,2,3]. We report the imaging of the magnetic excitation spectrum in presence of holes, fabricated by focussed ion beam milling, in the magnetic domains and domain walls of Landau structures by means of x-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM). Due to the very high lateral and temporal resolution the magnetization dynamics and the corresponding Eigen modes, which are characteristic for the vortexhole interaction, are investigated in detail. The experimental results are compared to micromagnetic simulations.

[1] M. Rahm et al., Appl. Phys. Lett. 85, 1553 (2004).
[2] T. Uhlig et al., Phys. Rev. Lett. 95, 237205 (2005).
[3] F. Hoffmann et al., Phys. Rev. B 76, 014416 (2007).