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MA: Magnetismus

MA 25: Hauptvortr
äge Thiaville / Kl
äui

MA 25.2: Hauptvortrag

Donnerstag, 11. März 2004, 14:30–15:00, H10

Magnetotransport and current induced domain wall propagation in ring structures with constrictions — •Mathias Kläui^1,2, C. A. F. Vaz², J. A. C. Bland², L. J. Heyderman³, W. Wernsdorfer⁴, and U. Rüdiger¹ — ¹Universität Konstanz, Fachbereich Physik, 78457 Konstanz, Deutschland — ²Cavendish Laboratory, Madingley Road, Cambridge, CB3 0HE, UK — ³LMN, Paul Scherrer Institut, 5232 Villigen-PSI, Schweiz — ⁴Laboratoire Louis Neel-CNRS, BP 138, 38274 Grenoble, Frankreich

The key to using magnetic nano-elements in applications is the presence of well-defined remanent states and reproducible switching. A possible geometry that fulfills these criteria is the ring geometry where due to the high symmetry particularly simple states and switching occur [1]. In addition to the flux-closure vortex state, the high-moment ’onion state’ was observed, which is characterized by two transverse or vortex head-to-head domain walls [1].

Owing to the constant curvature, rings have been found to be an ideal geometry for probing domain wall properties. Using magnetoresistance measurements, the behaviour of the different types of domain walls at constrictions has been investigated (attraction or repulsion). Furthermore the change of resistance as a domain wall moves into a constriction can be accounted for by the change in spin structure. Finally, high current densities are used to displace head-to-head domain walls. Such current-induced domain wall propagation is explained by a spin-torque effect. [2] [1] M. Kläui et al., Topical Review in J. Phys. Condens. Matter 15, 985 (2003) [2] M. Kläui et al., Appl. Phys. Lett. 83, 105 (2003)