Berlin 2005 – scientific programme
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MA: Magnetismus
MA 27: Spindynamik II
MA 27.10: Talk
Tuesday, March 8, 2005, 17:30–17:45, TU H1012
Small and large angle precession in exchange biased bilayers — •Markus C. Weber1, Hans Nembach1, Burkard Hillebrands1, and Jürgen Fassbender2 — 1Fachbereich Physik und Forschungsschwerpunkt MINAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany — 2Institut für Ionenstrahlphysik und Materialforschung, Forschungszentrum Rossendorf, 01314 Dresden, Germany
Small and large angle excitations in exchange bias systems have been investigated in real time by means of all-optical pump-probe experiments. Due to an increased spin temperature upon photoexcitation, an unpinning of the interfacial exchange coupling takes place resulting in a collapse of the unidirectional anisotropy. In terms of an internal pulse field the excess energy of the spin system leads to the excitation of a high frequency precessional response. The magnitude of the internal pulse field can be controlled by the absorbed photons [1]. Hence, the precessional motion depending on the precession angle can be investigated. The extracted Gilbert parameter does not depend on the magnitude of the internal pulse field. Both small and large angle precession can be modeled within the Landau-Lifshitz-Gilbert framework. Employing the antiferromagnetic thickness dependence of the exchange bias field, the exchange bias field dependence of the Gilbert parameter was investigated. The dissipation rate increases linearly with the exchange bias field magnitude which can be understood taking local fluctuations of the interfacial exchange coupling as an additional dissipation mechanism into account [2].
[1] M. C. Weber et al., Phys. Rev. B, submitted. [2] M.C. Weber et al., J. Appl. Phys., in press.