Direct Imaging of Chiral Domain Walls and Néel‐Type Skyrmionium in Ferrimagnetic Alloys
Boris Seng, Daniel Schönke, Javier Yeste, Robert M. Reeve, Nico Kerber, D. Lacour, Jean-Loïs Bello, N. Bergeard, Fabian Kammerbauer, Mona Bhukta, Tom Ferté, Christine Boeglin, F. Radu, Radu Abrudan, T. Kachel, S. Mangin, M. Hehn, Mathias Kläui
Abstract
Abstract The evolution of chiral spin structures is studied in ferrimagnetic Ta/Ir/Fe/GdFeCo/Pt multilayers as a function of temperature using scanning electron microscopy with polarization analysis (SEMPA). The GdFeCo ferrimagnet exhibits pure right‐handed Néel‐type domain wall (DW) spin textures over a large temperature range. This indicates the presence of a negative Dzyaloshinskii–Moriya interaction that can originate from both the top Fe/Pt and the Co/Pt interfaces. From measurements of the DW width, as well as complementary magnetic characterization, the exchange stiffness as a function of temperature is ascertained. The exchange stiffness is surprisingly more or less constant, which is explained by theoretical predictions. Beyond single skyrmions, it is identified by direct imaging a pure Néel‐type skyrmionium, which due to the expected vanishing skyrmion Hall angle, is a promising topological spin structure to enable applications by next generation of spintronic devices.