Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 7: Micro and Nanostructured Magnetic Materials II

MA 7.7: Vortrag

Montag, 25. Februar 2008, 16:45–17:00, EB 301

Temperature-dependent investigation of domain wall depinning in nanowires by ballistic Hall micromagnetometry — •Peter Lendecke, René Eiselt, Ulrich Merkt, and Guido Meier — Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Universität Hamburg, Jungiusstraße 11, 20355 Hamburg, Germany

We use ballistic Hall micromagnetometry [1] to determine depinning fields of domain walls in permalloy nanowires in the temperature range between 1.6 and 50 K. The walls are pinned in lithographically defined triangularly shaped constrictions. Pinning and depinning of single domain walls is detected via the stray field of the walls. The high sensitivity of our Hall magnetometer to the local micromagnetic structure allows the detection of single domain walls and a distinction of different wall types. A strong decrease of depinning fields at raised temperature is observed. For temperatures above 20 K additional domain wall types occur that can be distinguished by different stray field strengths as well as by different depinning field values [2]. We fit the depinning field decrease to a model describing the depinning process by hopping over a single energy barrier [3].

[1] A. K. Geim et al., Appl. Phys. Lett. 71, 2379 (1997)

[2] P. Lendecke, R. Eiselt, U. Merkt, and G. Meier, submitted.

[3] J. Kurkijärvi, Phys. Rev. B. 6, 832 (1972).