Dresden 2003 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
MA: Magnetismus
MA 19: Mikro- und nanostrukturierte Materialien I
MA 19.3: Vortrag
Mittwoch, 26. März 2003, 15:45–16:00, HSZ/405
Magnetic states and controlled switching by pinning of domain walls at notches in mesoscopic ferromagnetic rings. — •Mathias Kläui1, C.A.F. Vaz1, J.A.C. Bland1, L. Heyderman2, and W. Wernsdorfer3 — 1Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK — 2Paul Scherrer Institut, Villigen, Switzerland — 3Laboratoire CNRS-L. Neel, Grenoble, France
The key to using magnetic nano-elements in applications is a detailed understanding and precise control of magnetic switching. To achieve this one needs firstly to have a well-defined and reproducible remanent state and secondly, the switching process itself must be simple and reproducible. A possible geometry that fulfills these criteria is the ring geometry, and in particular narrow ferromagnetic rings, which have recently become the focus of intense interest. Nanoscale PEEM and SEMPA imaging of epitaxial and polycrystalline rings shows the existence of different magnetic states (flux closure vortex state; onion state with head-to-head domain walls with different spin structures). The switching is found to be classifiable into three categories, according to the number of transitions (single, double, triple) a ring undergoes during a hysteresis cycle. Furthermore anisotropic magnetoresistance measurements of narrow ferromagnetic rings with non-magnetic contacts allow us to easily determine the domain wall positions and this then allows us to investigate the strength of the domain wall pinning at constrictions (notches). Furthermore we measure the MR contribution of the domain wall for different sized notches and different applied fields. We then use notches of different sizes to control the switching in the rings.