Dresden 2020 – scientific programme

The DPG Spring Meeting in Dresden had to be cancelled! Read more ...

Parts | Days | Selection | Search | Updates | Downloads | Help

MA: Fachverband Magnetismus

MA 49: Focus Session: Higher-Order Magnetic Interactions – Implications in 2D and 3D Magnetism II

MA 49.4: Talk

Thursday, March 19, 2020, 16:00–16:15, HSZ 04

Short- and long-range toroidal order in nanomagnetic arrays — •Jannis Lehmann¹, Amadé Bortis¹, Naëmi Leo^2,3, Claire Donnelly², Peter Derlet², Laura J. Heyderman^1,2, 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.