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MA: Magnetismus

MA 32: Magnetic Particles / Clusters

MA 32.6: Vortrag

Donnerstag, 30. März 2006, 16:30–16:45, HSZ 401

Superferromagnetic domains in granular multilayers observed by X-PEEM and transmission x-ray microscopy — •S. Bedanta¹, T. Eimüller², P. Fischer³, W. Kleemann¹, D.- H. Kim³, E. Amaladass⁴, S. Cardoso⁵, and P. P. Freitas⁵ — ¹Universität Duisburg-Essen, D-47048 Duisburg, Germany — ²Ruhr-Universität Bochum, D-44780 Bochum, Germany — ³Lawrence Berkeley National Laboratory, Berkeley CA 94720, USA — ⁴Max-Planck-Institut fur Metallforschung, 70569 Stuttgart, Germany — ⁵INESC, Rua Alves Redol 9-1, 1000 Lisbon, Portugal

Due to interparticle interactions, a collective superferromagnetic domain state is encountered in non-percolated granular multilayers [Co₈₀Fe₂₀(t_n)/Al₂O₃(3nm)]₁₀, where t_n represents the nominal thickness of CoFe [1-3]. Based on x-ray magnetic circular dichroic element-specific contrast, photoemission electron microscopy (X-PEEM) and transmission soft x-ray microscopy (XM-1), both at ALS, Berkeley, proved successful to image superferromagnetic domains at different external applied fields. Stripe domains stretched along the easy in-plane axis, but exhibiting irregular walls and hole-like internal structures ("domains in domains") are revealed by X-PEEM on a sample with t_n = 1.3nm. More compact domains with a few µm in size were imaged by XM-1 on a sample with t_n = 1.6nm. Their growth was recorded during magnetization reversal under near-coercive magnetic fields.

[1] W. Kleemann et al., Phys. Rev. B 63, 134423 (2001).

[2] X. Chen et al., Phys. Rev. Lett. 89, 137203 (2002).

[3] S. Bedanta et al., Phys. Rev. B 72, 024419 (2005).