Fig. 1

Direct observation of stabilized Bloch point (BP) structures. a–c Schematic diagram of three possible configurations of a BP with skyrmion charge q = + 1, namely, hedgehog (a), circulating (b), and spiralling (c) configurations where the colour indicates the orientation of magnetization. d In-plane (IP) and out-of-plane (OOP) magnetic components observed by magnetic transmission soft X-ray microscopy (MTXM), and the corresponding magnetic structures determined by micromagnetic simulations. Zoomed images for magnetic configurations near vortex core structures are also inserted. The black and white contrasts in the images of the IP (OOP) magnetic component represent the magnetizations oriented in the left and right directions on the disk plane (perpendicular upward and downward to the disk plane), respectively. e Images of the distorted vortex core structures with no BP (left), a single BP (middle), and double BPs (right), and the configurations of the BPs embedded in the vortex cores. The OOP magnetic components with m_z>  + 0.8 (red) and m_z < −0.8 (blue) were extracted and the BP configurations were obtained by interpolation from the simulated vortex core structures. The single BP is characterized by q = −1, while the double BPs are defined by q = −1 and +1, respectively. The single-BP core structure here is referred to as type I. Scale bars in (d, e) correspond to 500 nm and 50 nm, respectively