Speaker: Shilei ZhangTitle: Structural Variations of the Three-Dimensional Skyrmion Strings*

Magnetic skyrmions are planar microscopic magnetization swirls that extend into the third dimension in form of strings. Recently, the three-dimensional (3D) aspect of the skyrmion strings have attracted great attention in magnetism, as the rich structural variations along the string offers an ideal playground in studying the fundamental physical topics, such as topological defects and emergent phenomena in condensed matters. However, their 3D magnetic characterizations, as well as the effective control of the strings' configurations remain challenging. In this talk, we will discuss our recent progress in addressing these issues. Characterization-wise, we developed a series of soft x-ray techniques that can uniquely probe the detailed string structures that are buried beneath the surface of a sample. Material-wise, we introduce a helimagnet/multilayer heterostructure system that merges two distinct skyrmion species into one. Exploiting the interfacial coupling, exotic 3D topological phases can be stabilized, which subsequently leads to additional transport effects. We hope these findings will provide new routes in studying topological magnetism.