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MA: Fachverband Magnetismus
MA 3: Micro- and nanostructured Materials
MA 3.8: Talk
Monday, March 7, 2016, 11:30–11:45, H32
Toroidal ordering in a compensated nanomagnetic lattice — •Jannis Lehmann1, Claire Donnelly1,2, Sebastian Gliga1,2, Peter Derlet2, Dennis Meier1, Laura Heyderman1,2, and Manfred Fiebig1 — 1Department of Materials, ETH Zurich, Switzerland — 2Paul-Scherrer-Institute, Villigen PSI, Switzerland
Two-dimensional magnetic nanostructures show interesting ordering effects due to dipolar stray-field coupling of single macro-spins that yield, e.g., frustrated spin-ice behaviour. To obtain a net toroidal moment, the spins in a unit cell have to form a magnetic whirl. Here we present a nanomagnetic lattice that exhibits toroidal domains, which currently attract great attention due to their intrinsic space- and time-antisymmetric properties. Our structural unit cell consists of four lithographically written sub-micron permalloy islands that are arranged on a silicon substrate forming the edges of a square. We discuss the as-grown magnetic order and the influence of different island separations on the resulting toroidal domain structure. Using magnetic force microscopy, we show that domains of opposite chirality emerge that are separated by well-defined domain-wall states. Our results demonstrate the possibility of engineering the as-grown magnetic state. By tayloring the relative distances between the nanomagnets, we can control the toroidal domain size and the domain-wall geometry. This enables us to investigate the quantum-mechanically defined toroidal moment at a mesoscopic length scale, i.e., on a technically accessable classical level.