Dresden 2009 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 40: Poster II: Bio- and Molecular Magnetism (1-9); Magnetic Coupling Phenomena/Exchange Bias (10-15); Magnetic Particlicles and Clusters (16-29); Micro and Nanostructured Magnetic Materials (30-51); Multiferroics (52-64); Spin Injection in Heterostructures (65-67); Spin-Dyn./Spin-Torque (68-93); Spindependent Transport (94-108)

MA 40.50: Poster

Freitag, 27. März 2009, 11:00–14:00, P1A

Vortex stabilization in magnetic trilayer dots — •Philipp Szary, Oleg Petracic, and Hartmut Zabel — Institut für Experimentalphysik/Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum

We have investigated the spin structure in Co/Al₂O₃/Py (Py=Ni₈₀Fe₂₀) trilayer nanodots both via micromagnetic simulation and experimentally by MOKE, SQUID and MFM measurements. Depending on the dot size isolated Py layers would show either a vortex or single domain state during magnetization reversal. However, the Co layer stays always in the single domain state. After combining both dots in a stack separated by an insulating layer, we observe three scenarios of reversal processes in the soft ferromagnetic Py layer due to dipolar coupling to the hard ferromagnetic Co layer, i.e. (1) stabilization, (2) triggering of the vortex state and (3) occurrence of a 360^∘ domain wall. We have constructed a phase diagram, where regions of vortex stabilization, triggering and occurrence of a 360^∘ domain wall are marked. We also have studied the case of a polycrystalline Co layer. Here the phase diagram is more complex with additional regions, i.e. a vortex in the Co layer, a vortex in both Co and Py layer or a destabilization of the vortex due to dipolar coupling.