Berlin 2005 – wissenschaftliches Programm

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MA: Magnetismus

MA 17: Spinabh
ängiger Transport II

MA 17.1: Vortrag

Montag, 7. März 2005, 10:30–10:45, TU H1012

Influence of domain wall stray fields on the magnetization reversal of an FeNi/Al₂O₃/Co tunnel junction — •K. Fukumoto¹, W. Kuch¹, J. Vogel², R. Hertel¹, J. Camarero³, S. Pizzini², F. Romanens², M. Bonfim², A. Fontaine², and J. Kirschner¹ — ¹Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany — ²Laboratoire Louis Néel, CNRS, 25 avenue des Martyrs, B. P. 166, F-38042 Grenoble Cedex 9, France — ³Dpto. Física de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain

Understanding and controlling the magnetization reversal of magnetic trilayers in which two ferromagnetic layers (FM) are coupled across a non-magnetic spacer layer is an important issue for the investigation of many interesting phenomena as well as for applications. We used a novel combination of photoelectron emission microscopy, x-ray magnetic circular dichroism and stroboscopic pump-probe technique, in which nanosecond-short magnetic field pulses (the pump) are synchronised to x-ray pulses from BESSY (the probe), to study the magnetization reversal dynamics of a permalloy layer in a FeNi/Al₂O₃/Co magnetic tunnel junction with temporal, layer, and spatial resolution. We observe that the stray field from domain walls in the magnetically harder Co layer plays an important role in the magnetization reversal of the softer permalloy layer. During the field pulse, magnetic domains in the permalloy layer nucleate preferentially above domain walls in the Co layer. This is compared to micromagnetic simulations of a hard–soft trilayer system.