Berlin 2005 – wissenschaftliches Programm

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MA: Magnetismus

MA 31: Magnetische Partikel/Cluster II

MA 31.6: Vortrag

Mittwoch, 9. März 2005, 12:15–12:30, TU H1012

Polarized Neutron Reflectometry and magnetometry studies on granular multilayers — •Subhankar Bedanta¹, Emmanuel Kentzinger², Oleg Petracic¹, Wolfgang Kleemann¹, Ulrich Rücker², Amitesh Paul², Thomas Brückel², S. Cardoso³, and P. P. Freitas³ — ¹Angewandte Physik, Universität Duisburg-Essen, D-47048 Duisburg, Germany — ²Institut für Festkörperforschung, Forschungszentrum Jülich, D-52425 Jülich, Germany — ³INESC, Rua Alves Redol 9-1, 1000, Lisbon, Portugal

Polarized neutron reflectivity (PNR) and magnetometry studies have been performed on the granular multilayers [Co₈₀Fe₂₀(t_n)/Al₂O₃(3nm)]₁₀ for two different nominal thicknesses t_n = 1.3 nm (non-percolating superferromagnet) and t_n = 1.6 nm (percolating ferromagnet). The ac-susceptibility components measured as a function of frequency, temperature and field amplitudes show similar results as obtained from recent simulations. They hint at sliding and switching regimes of pinned domain walls. This is also confirmed by PNR measurements of the slowly relaxing magnetization reversal, which does not show any spin flip scattering. For the percolated sample fast relaxation is found, which is accompanied by two enhanced satellites around the first Bragg peak. This is probably due to an oscillating magnetization between FeCo layers with a period of five bilayers along the multilayer stack.