Fig. 4

Time-resolved measurements for the dynamics of a Bloch point (BP). a, b Representative images of the vortex core structures with (a) and without (b) a BP (the first row) along with positions of core structures measured at t = 0, 2, 3.5, 4.5, 8, 9 ns during their dynamic processes triggered by the injection of a field pulse with an amplitude of 50 Oe and the width of 3 ns in the +x-direction. The blue and red dotted lines in zoomed images correspond to the initial position of the core structures with and without BP. The red and blue lines indicate perturbed positions (t > 0) of the single-BP core and non-BP core. Scale bars in (a, b) correspond to 500 nm (representative images) and 200 nm (zoomed images), respectively. c Quantitatively analysed differences between initial (t = 0, black line) and perturbed positions (t > 0) of the single-BP core (blue line) and non-BP core structure (red line). The experimental error bars are taken at one standard deviation. d Trajectory curves of the simulated dynamic motions of the BP and vortex cores with up (VC^↑) and down (VC^↓) polarizations in the single-BP and non-BP cores (scale bar: 50 nm). e, f The variations of normalized y-components of magnetizations, < m_y > = < M_y/M_s > (e) and total energy (f) during the dynamic relaxation processes of the single-BP and non-BP cores. Raw data of Fig. 4c are provided as the Source Data files

Source Data