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

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 N el 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 N el 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 device