Direct Imaging of Chiral Domain Walls and Neel-Type Skyrmionium in Ferrimagnetic Alloys

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 Neel-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 Neel-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.

Automated summary

Chiral spin structures in ferrimagnetic Ta/Ir/Fe/GdFeCo/Pt multilayers were studied using scanning electron microscopy with polarization analysis (SEMPA) as a function of temperature. GdFeCo ferrimagnet exhibited right-handed Neel-type domain wall (DW) spin textures over a large temperature range, indicating a negative Dzyaloshinskii-Moriya interaction from both the top Fe/Pt and Co/Pt interfaces. Measurements of the DW width and complementary magnetic characterization confirmed the relatively constant exchange stiffness with temperature, supporting theoretical predictions. Additionally, a pure Neel-type skyrmionium was identified through direct imaging, showing potential for application in next-generation spintronic devices due to the expected vanishing skyrmion Hall angle.