Berlin 2005 – scientific programme

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MA: Magnetismus

MA 15: Magnetische Kopplungsph
änomene / Exchange Bias

MA 15.5: Talk

Saturday, March 5, 2005, 15:00–15:15, TU H1028

Magnetization reversal in CoFe/IrMn exchange biased structures — •Christine Hamann¹, Jeffrey McCord¹, Rudolf Schäfer¹, Ludwig Schultz¹, and Roland Mattheis² — ¹Leibniz-Institut für Festkörper- und Werkstoffforschung (IFW), Helmholtzstraße 20, 01069 Dresden — ²Institut für Physikalische Hochtechnologie e.V. (IPHT), Albert - Einstein - Str. 9, 07745 Jena

For fundamental understanding of exchange biased systems, the magnetization reversal process of Co₉₀Fe₁₀(20nm)/Ir₂₃Mn₇₇ bilayer structures with varying antiferromagnetic layer thickness (0-10nm) has been investigated by means of Kerr microscopy and spatially resolved magneto-optical magnetometry. At the onset of exchange bias (2.5nm IrMn), the bilayers exhibit a misalignment of the effective easy magnetization axis relative to the direction of the deposition field. The magnetization reversal of the systems with 2.5-10nm IrMn first takes place by small angle magnetization rotation and generation of multi-domain configurations that are finally annihilated by domain wall movement. The amount of rotation strongly depends on the field direction, as there is a distinct asymmetry between forward and recoil branch. Hereby, the asymmetry also strongly depends on the misalignment between the external field and the true easy axis. Moreover, creeping effects depending on IrMn layer thickness have been observed. The results are discussed in terms of reversible and irreversible antiferromagnetic contributions to the reversal process.