The creation and annihilation of magnetic skyrmions are mediated by three-dimensional topological defects known as Bloch points. Investigation of such dynamical processes is important both for understanding the emergence of exotic topological spin textures, and for future engineering of skyrmions in technological applications. However, while the annihilation of skyrmions has been extensively investigated in two dimensions, in three dimensions the phase transitions are considerably more complex. We report field-dependent experimental measurements of metastable skyrmion lifetimes in an archetypal chiral magnet, revealing two distinct regimes. Comparison to supporting three-dimensional geodesic nudged elastic band simulations indicates that these correspond to skyrmion annihilation into either the helical and conical states, each exhibiting a different transition mechanism. The results highlight that the lowest energy magnetic configuration of the system plays a crucial role when considering the emergence and stability of topological spin structures via defect-mediated dynamics.

磁性斯格明子的产生和消灭是由称为布洛赫点的三维拓扑缺陷介导的。研究此类动力学过程对于理解奇异拓扑自旋纹理的出现以及未来在技术应用中的斯格明子工程都很重要。然而，虽然斯格明子的湮灭已在二维中得到广泛研究，但在三维中，相变要复杂得多。我们报告了原型手征磁铁中亚稳态斯格明子寿命的场相关实验测量，揭示了两种不同的制度。与支持三维测地线轻推弹性带模拟的比较表明，这些对应于斯格明子湮灭为螺旋和圆锥状态，每个都表现出不同的过渡机制。结果强调，在通过缺陷介导的动力学考虑拓扑自旋结构的出现和稳定性时，系统的最低能量磁性配置起着至关重要的作用。