The development and characterization of three-dimensional (3D) topological magnetic textures has become an important topic in modern magnetism both for fundamental and technological perspectives. Among the novel 3D spin textures, skyrmionic cocoons have been successfully stabilized in magnetic multilayers having a variable thickness of the ferromagnet in the vertical direction of the stack. These ellipsoidal 3D magnetic textures remain vertically confined in a fraction of the total thickness, whereas, coexisting with fully columnar skyrmions. Here, we use xray holography with about 15-nm lateral resolution to investigate how their properties depend on the field and temperature. We observe circular objects with different amplitude of contrast, which evidences the presence of different 3D objects located in various vertical parts of the multilayer. Moreover, whereas, sweeping an out-of plane magnetic field, we witness an attractive interaction between cocoons located at various heights, mainly due to the stray field, which impacts their horizontal positionings. The x-ray holography measurements also allow to determine the size of the cocoons at remanence, which at room temperature, possess diameters close to 100 nm on average. Combining this transmission technique with magnetic force microscopy and micromagnetic simulations gives a precise insight into the 3D distribution of the magnetization, which demonstrates the 3D nature of skyrmionic cocoons.

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• Magnetic texture
• Magnetism
• Spin texture
• Magnetic multilayers
• Spin
• Holography