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MA: Fachverband Magnetismus

MA 20: POSTER Ib

MA 20.45: Poster

Tuesday, March 17, 2015, 09:30–13:00, Poster A

Capturing a Skyrmion with a Hole — •Jan Müller and Achim Rosch — Institut für Theoretische Physik, Universität zu Köln, Deutschland

Stable magnetic whirls in chiral magnets, so-called skyrmions, can be manipulated by ultrasmall current densities. We study both analytically and numerically the interactions of a single skyrmion in two dimensions with a small hole in the magnetic layer. Results from micromagnetic simulations are in good agreement with effective equations of motion obtained from a generalization of the Thiele approach. Skyrmion-defect interactions are described by an effective potential with both repulsive and attractive components.

For small current densities a previously pinned skyrmion stays pinned whereas an unpinned skyrmion moves around the impurities and never gets captured. For higher current densities, however, single holes are able to capture moving skyrmions. The maximal cross section is proportional to the skyrmion radius and to the square root of the Gilbert damping. For large currents all skyrmions are depinned. Small changes of the magnetic field strongly change the pinning properties, one can even reach a regime without pinning at all. We also show that a small density of holes can effectively accelerate the motion of the skyrmion and introduce a Hall effect for the skyrmion.