Three-dimensional tomographic imaging of skyrmionic cocoons using HERALDO
Phys. Rev. B 113, 174435 – Published 21 May, 2026
DOI: https://doi.org/10.1103/7tj3-byh2
Abstract
Uncovering the rich and intricate characteristics of three-dimensional (3D) magnetic textures is essential for functional materials such as magnetic multilayers, where the delicate balance of various magnetic interactions leads to complex 3D spin arrangements. Among these textures, skyrmionic cocoons—tubular 3D magnetic structures characterized by a closed magnetization surface wrapping around a core—have emerged as particularly intriguing. Stabilized by competing magnetic interactions, these textures reside within a fraction of the thickness of the magnetic material and exhibit a typical lateral size of approximately 100 nm. Here, we present a vector tomographic reconstruction of the 3D magnetization in aperiodic Pt/Co/Al chiral multilayers, where skyrmionic cocoons have been recently reported. Using soft x-ray holography with extended reference by autocorrelation linear differential operator (HERALDO), we acquire tomographic projections of the magnetic configuration with a constant out-of-plane field and reconstruct the full 3D magnetization vector field with a spatial resolution of approximately 30 nm, as determined by Fourier shell correlation. This resolution allows us to observe critical features of the cocoons, such as their vertical misalignment. Our findings provide direct three-dimensional insight into the internal structure, vertical extent, and chirality of skyrmionic cocoons, enabled by magnetic-field-compatible vector tomography and qualitatively supported by micromagnetic simulations.
