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MA: Fachverband Magnetismus

MA 44: Non-Skyrmionic Magnetic Textures

MA 44.7: Talk

Thursday, March 21, 2024, 17:00–17:15, EB 301

From Ferromagnetic Magnetostatics to Antiferromagnetic Topology: Antiferromagnetic Vortex States in NiO-Fe Nanostructures — Michał Ślezak¹, •Tobias Wagner², V.K. Bharadwaj², Anna Kozioł-Rachwał¹, Tomasz Ślezak¹, and Olena Gomonay² — ¹AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Kraków, Poland — ²Institut für Physik, JGU Mainz, Germany

Magnetic vortices are topological spin structures commonly found in ferromagnets. However, they are novel for antiferromagnets. In particular, Wu et al. observed the interface-exchange-coupling-dependent transfer of the Fe vortex state to the coupled CoO or NiO layer for patterned microstructures [1]. We experimentally demonstrate that in a nanostructured antiferromagnetic-ferromagnetic hybrid bilayer, a magnetic vortex naturally stabilizes by magnetostatic interactions in the Fe(110) and imprints onto the adjacent NiO(111) via interface exchange coupling. We assume the coupling to be collinear, as recently reported in continuous NiO(111)-Fe(110) bilayers by Ślȩzak et al. [2]. Our micromagnetic simulations elucidate the mechanism for the existence of antiferromagnetic vortex states [3]. We find that the interplay between the interface exchange coupling and the antiferromagnetic anisotropy plays a crucial role in locally reorienting the Néel vector out-of-plane in the prototypical in-plane antiferromagnet NiO and thereby stabilizing the vortices in the antiferromagnet. [1] Wu, J. et al. Nat. Phys. 7, 303-306 (2011). [2] Ślȩzak, M. et al. Nanoscale 12, 18091-18095 (2020). [3] Ślȩzak, M., Wagner, T. et al., in preparation.

Keywords: Interface Exchange Coupling; Micromagnetic Simulation; Antiferromagnetic-Ferromagnetic Bilayer; NiO-Fe; Magnetic Vortex State