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MA: Fachverband Magnetismus
MA 49: Focus Session: Higher-Order Magnetic Interactions – Implications in 2D and 3D Magnetism II
MA 49.4: Vortrag
Donnerstag, 19. März 2020, 16:00–16:15, HSZ 04
Short- and long-range toroidal order in nanomagnetic arrays — •Jannis Lehmann1, Amadé Bortis1, Naëmi Leo2,3, Claire Donnelly2, Peter Derlet2, Laura J. Heyderman1,2, and Manfred Fiebig1 — 1Department of Materials, ETH Zurich, Switzerland — 2Paul Scherrer Institute, Villigen PSI, Switzerland — 3CIC nanoGUNE, Donostia-San Sebastián, Spain
Ferrotoroidicity, i.e. the collective alignment of uniformly-oriented magnetic whirls that spontaneously form at the unit-cell level, is an elusive type of magnetically-compensated ferroic order. Since compounds displaying ferrotoroidicity are rare and difficult to identify because the access to their compensated magnetic order is experimentally challenging, we here make use of artificial planar nanostructures made from ferromagnetic building blocks as a versatile approach to design and study magnetic frustration or other phenomena. We introduce arrays of stray-field-coupled single-domain- or vortex-state nanomagnets of different geometry that exhibit emergent ferrotoroidic order at mesoscopic length scales. We perform magnetic force microscopy to achieve spatial access to the magnetic configuration and the toroidal domain pattern. By varying the arrangement of building blocks we tune the delicate competition of microscopic couplings between the nanomagnets. We find that this competition influences key observables of ferroic order as e.g. the domain size, the domain-wall configuration and the density of topological defects. We explain our observations by identifying different multipolar pathways to long-range order.