Berlin 2005 – wissenschaftliches Programm

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MA: Magnetismus

MA 27: Spindynamik II

MA 27.12: Vortrag

Dienstag, 8. März 2005, 18:00–18:15, TU H1012

Dynamics of magnetic domain wall motion: Dependence on wall energy, mobility, and Zeeman energy — •K. Fukumoto¹, W. Kuch¹, J. Vogel², 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

Nowadays the response time of magnetic recording devices is going down to the ns range. For the fast switching of magnetic trilayered systems it is important to know the factors influencing the speed of domain nucleation and subsequent domain wall propagation. We studied magnetic domain nucleation and wall motion in the permalloy layer of a magnetic-tunnel-junction like system by a novel combination of x-ray magnetic circular dichroism, photoelectron emission microscopy, and stroboscopic pump-probe technique. The expansion of micron-sized magnetic domains was followed with ns time resolution for various amplitudes of the external field. Since these applied external fields were well above the static coercive field, viscous wall motion was observed, in which the wall velocity is a linear function of the external field. The onset of domain expansion was observed to take place after the beginning of the pulse, with a delay depending on the pulse amplitude. This apparent delay in domain nucleation can be understood taking into account the domain wall energy, causing a lower domain wall speed when the domains are small.