Dresden 2009 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 25: Micro- and Nanostructured Magnetic Materials II

MA 25.9: Vortrag

Mittwoch, 25. März 2009, 16:45–17:00, HSZ 403

Hall micromagnetometry of domain walls in permalloy nanostructures — •Peter Lendecke¹, Lena Breitenstein¹, Stellan Bohlens², Guido Meier¹, and Ulrich Merkt¹ — ¹Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Universität Hamburg — ²I. Institut für Theoretische Physik, Universität Hamburg

We investigate domain-wall depinning in permalloy nanowires and the hysteresis of micron-sized square platelets by ballistic Hall micromagnetometry. The technique allows to measure the stray field of individual nanostructures between liquid helium temperature and 50 K. The pinning and depinning of single domain walls at constrictions is detected non-invasively by sensing the stray field of the walls [1]. Results on the temperature dependence of depinning fields at constrictions of different sizes as well as experiments on current-assisted depinning are presented. By measuring the stray field of square thin-film platelets we are able to investigate their hysteresis loop at low temperatures. Nucleation of a Landau pattern, displacement of the vortex in its centre by an in-plane external field, and vortex annihilation are clearly identified by analyzing minor loops and return branches [2]. These results are corroborated by magnetic-force microscopy images and micromagnetic simulations.
P. Lendecke, R. Eiselt, U. Merkt, and G. Meier, J. Appl. Phys. 103, 073909 (2008).
L. Breitenstein, P. Lendecke, S. Bohlens, G. Meier, and U. Merkt, J. Appl. Phys. 104, 083909 (2008).