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MA: Fachverband Magnetismus

MA 37: Skyrmions III

MA 37.5: Talk

Thursday, March 21, 2024, 10:30–10:45, EB 301

Dipolar-stabilized skyrmions transparent for TEM — •Andrii Savchenko¹, Vladyslav Kuchkin², Filipp Rybakov³, and Nikolai Kiselev¹ — ¹Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany — ²Science Institute, University of Iceland, 101 Reykjavík, Iceland — ³Department of Physics and Astronomy, Uppsala University, SE-75120 Uppsala, Sweden

In magnetic multilayers with asymmetric interfaces between magnetic and nonmagnetic layers, the interfacial Dzyaloshinskii-Moriya interaction (iDMI) can give rise to dipolar-stabilized skyrmions (magnetic bubbles) with Neel-type domain walls (DWs). For these DWs, the Lorentz Transmission Electron Microscopy (LTEM) contrast is absent when the electron beam is incident normal to the film surface and occurs only when the sample is tilted with respect to the beam. Such behavior in LTEM is often used to confirm the presence of iDMI. We have found another type of DW that exhibits the same behavior in LTEM. These Bloch-type DWs possess alternating chirality in adjacent layers. The skyrmions with these DWs can be observed in multilayers with weak interlayer exchange coupling (IEC) and without iDMI. The LTEM contrast for these skyrmions becomes visible only when the sample is tilted relative to the electron beam. In multilayers without IEC, dipolar skyrmions with alternating chirality and fixed chirality in the DWs have nearly identical energies and can coexist in the whole range of magnetic fields. Thus, the binary data can be efficiently encoded by the sequence of skyrmions of those two types.

Keywords: skyrmion; Lorentz TEM; domain wall; multilayer; alternating chirality