Direct imaging of topological phase discontinuities in chiral spin textures via electron ptychography beyond diffraction-limited resolution*

Real-space imaging of magnetic structures can provide crucial information for understanding many magnetic phenomena. Here, utilizing a new electron microscope detector, EMPAD, we resolve the internal fine structure of skyrmions in single crystal FeGe using Lorentz STEM and electron ptychography. We have unambiguously uncovered the topological phase discontinuities near the skyrmion lattice dislocation and boundaries. We also demonstrate a significant resolution improvement using electron ptychography, allowing magnetic imaging beyond the diffraction limit imposed by the electron optics. Magnetic domain images from ultrathin metallic multilayer films show the outstanding detection limit of our new imaging method. This new direct imaging technique can be applied to determine complex chiral spin structures in a wide variety of materials.