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Magnetic domains and magnetization reversal of ion-induced magnetically patterned RKKY-coupled Ni81Fe19/Ru/Co90Fe10 films

Fassbender, J.; Bischoff, L.; Mattheis, R.; Fischer, P.

Abstract

Pure magnetic patterning by means of ion beam irradiation of magnetic thin films and multilayers result from a post deposition local modification of the interface structure with only minor effects on the film topography. In the study presented here a 50 keV fine focused Co ion beam was used to change the coupling in a Ni81Fe19/Ru/Co90Fe10 structure from antiferromagnetic to ferromagnetic on a micron scale. Thereby an artificial structure with locally varying interlayer coupling and therefore magnetization alignment is produced. High-resolution full-field x-ray microscopy is used to determine the magnetic domain configuration during the magnetization reversal process locally and layer resolved due to the element specific contrast in circular x-ray dichroism. In the magnetically patterned structure there is in addition to the locally varying interlayer exchange coupling across the Ru layer also the direct exchange coupling within each ferromagnetic layer present. Therefore the magnetization reversal behaviour of the irradiated stripes is largely influenced by the surrounding magnetic film. We found that at the boundaries between irradiated and non-irradiated areas magnetic domain walls form during magnetization reversal with a magnetization component perpendicular to the film plane. This can be explained by the stray field generated by this domain wall which is partially compensated by a corresponding domain wall in the second ferromagnetic layer with opposite direction. It is expected that a pure magnetic patterning, as demonstrated here, can provide an additional degree of freedom in tailoring the overall magnetic properties of thin multilayer structures.

Keywords: ion irradiation; magnetic patterning; magnetism; RKKY coupling; magnetic domains; x-ray microscopy; XMCD

Permalink: https://www.hzdr.de/publications/Publ-7544