Dresden 2006 – wissenschaftliches Programm

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MA: Magnetismus

MA 20: Poster: Films(1-36) Transp(37-56) Ex.Bias(57-67) Spindyn(68-80) Micromag(81-95) Particle(96-109) Imag.+Surface(110-113) Spinelectr(114-122) Theory+Micromag(123-131) Spinstr+Aniso(132-142) MagMat(143-156) Meas(157,158) MolMag+Kondo(159-162) Postdead(163-)

MA 20.30: Poster

Dienstag, 28. März 2006, 15:15–19:15, P1

Magnetization dynamics of an unbiased permalloy thin-film microstructure and the free layer of a synthetic spin valve — •F. Wegelin¹, A. Krasyuk¹, D. Valdaitsev¹, S. Nepijko¹, H.J. Elmers¹, G. Schönhense¹, I. Krug², and C.M. Schneider² — ¹Johannes Gutenberg-Universität Mainz, Institut für Physik, D-55128 Mainz, Germany — ²Institut für Festkörperforschung IFF-6, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany

Applying a biasing magnetic field on a thin micron-sized permalloy (Py) layer leads to suppression of domain wall creation and of Landau-Liftschitz flux-closure pattern formation. The magnetization dynamics of such a pinned and almost uniformly magnetized platelet differs from that of an unbiased particle because the pinning field defines the magnetic ground state of the system. We compare the dynamic properties of a single unbiased Py layer and the topmost Py layer in a GMR (Giant MagnetoResistive [1]) spin valve stack. Whereas the oscillatory behavior at 0.5 GHz of the single Py platelet exhibits considerable contribution of higher harmonics resulting in a shift of the 180^∘ Neél wall [2], the magnetization within the free layer of the spin valve rotates coherently performing a critically damped oscillation. Our investigations have been performed using TR-XMCD-PEEM (Time Resolved Photoemission Electron Microscopy exploiting the X-ray Magnetic Circular Dichroism) [3] with a time resolution of 15 ps.

[1] B. Dieny et al., Phys. Rev. B 43 (1991) 1297

[2] A. Krasyuk et al. Phys. Rev. Lett. 95 (2005) 207201

[3] A. Krasyuk et al. Appl. Phys. A 76 (2003) 863