Berlin 2005 – wissenschaftliches Programm

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MA: Magnetismus

MA 20: Poster:Schichten(1-29),Spintrsp(30-45),Ex-Bias(46-63),Spindyn(64-75),Mikromat.(76-80),Cluster(81-94),Abbv.(95-99),Obflm(100-02),SpElek.(103-09),E-Theo(110-14),Mikromag.(115-16),Spin+PÜ(117-26),Mag.Mat.(127-51),Meth.(152-55),Mol.Mag(156-59),Kondo(160-65

MA 20.57: Poster

Montag, 7. März 2005, 14:00–18:00, Poster TU C

Magnetization Reversal in Exchange Biased Multilayers with Field Direction — •Amitesh Paul, Emmanuel Kentzinger, Ulrich Rücker, Daniel Bürgler, and Thomas Brückel — Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany

The magnetization reversal in exchange-biased multilayers is studied by specular reflection and off-specular scattering of polarized neutrons for polycrystalline [Ir₂₀Mn₈₀(6.0 nm)/Co₈₀Fe₂₀(3.0 nm)]₁₀ multilayers. For increasing and decreasing applied fields, we have observed earlier symmetric and sequential reversal only via domain formation [1], when the applied field direction was along the exchange bias direction. In the present study, the CoFe layer remagnetizes symmetrically for both field branches in an uniform (via coherent rotation) as well as non-uniform mode (via domain formation) for different directions (90 and 45 deg.) of the applied fields w.r.t. the unidirectional anisotropy direction. We observe the enhanced spin-flip specular intensity at the HADAS reflectometer [1] indicating coherent rotation of the in-plane component of magnetization perpendicular to the field due to the variation of the field direction, which is in agreement with the theoretical model of Beckmann et al [2]. However, we show that such uniform mode of reversal can take place irrespective of the underlying domain wall motion. The small scale magnetization fluctuations as revealed by off-specular spin-flip scattering at reversal points clearly demonstrates this for different field directions.

[1] A. Paul et al, Phys. Rev. B (in press) 2004.

[2] B. Beckmann et al, Phys. Rev. Lett. 91, 187201, 2004.