Magnetic skyrmions are key candidates for applications in memory, logic and neuromorphic computing. An essential property is their topological protection that is caused by the swirling spin texture and described by a robust integer winding number. However, this protection is strictly enforced only in the continuum, and so the atomic lattice present in all real materials leaves a loophole for switching the winding number. Hence, understanding the microscopic mechanism of this unwinding is crucial for enhancing the stability of skyrmions. Here we use spin-polarized scanning tunnelling microscopy to locally probe skyrmion annihilation by individual hot electrons. We tune the collapse rate by up to four orders of magnitude by using an in-plane magnetic field, and observe distinct transition rate maps that either are radial symmetric or exhibit an excentric hotspot. We compare these maps to atomistic spin simulations based on parameters obtained from first-principles calculations and find that the maps are explained by a radial symmetric collapse at zero in-plane magnetic field and a transition to the recently predicted chimera collapse at finite in-plane magnetic fields. These insights into the transient state of the skyrmion collapse will enable future enhancement of skyrmion stability and designs for intentional skyrmion switches.

磁性斯格明子是内存、逻辑和神经形态计算应用的关键候选者。一个基本属性是它们的拓扑保护，这是由旋转自旋纹理引起的，并由稳健的整数绕组数描述。然而，这种保护只在连续体中严格执行，因此所有真实材料中存在的原子晶格留下了切换绕组数的漏洞。因此，了解这种展开的微观机制对于提高斯格明子的稳定性至关重要。在这里，我们使用自旋极化扫描隧道显微镜来局部探测单个热电子对斯格明子的湮灭。我们通过使用平面内磁场将塌陷率调整多达四个数量级，并观察不同的过渡率图，它们要么是径向对称的，要么表现出偏心热点。我们将这些图与基于从第一性原理计算获得的参数的原子自旋模拟进行比较，发现这些图可以通过零平面内磁场处的径向对称塌陷和最近预测的有限平面内嵌合塌陷的过渡来解释磁场。这些对斯格明子坍缩瞬态的见解将有助于未来增强斯格明子的稳定性和设计有意的斯格明子开关。我们将这些图与基于从第一性原理计算获得的参数的原子自旋模拟进行比较，发现这些图可以通过零平面内磁场处的径向对称塌陷和最近预测的有限平面内嵌合塌陷的过渡来解释磁场。这些对斯格明子坍缩瞬态的见解将有助于未来增强斯格明子的稳定性和设计有意的斯格明子开关。我们将这些图与基于从第一性原理计算获得的参数的原子自旋模拟进行比较，发现这些图可以通过零平面内磁场处的径向对称塌陷和最近预测的有限平面内嵌合塌陷的过渡来解释磁场。这些对斯格明子坍缩瞬态的见解将有助于未来增强斯格明子的稳定性和设计有意的斯格明子开关。