Soong Geun Je: Topological properties of the familyof magnetic skyrmions

Title: Topological properties of the family of magnetic skyrmions Abstract: Magnetic systems exhibit a variety of fascinating spin textures, which can be classified by their characteristic topological numbers. For example, magnetic skyrmions are of particular interest due to their emergent electromagnetism and their potential for the information carriers at the nanoscale. For implementing magnetic skyrmion-based devices, understanding the topological properties of magnetic skyrmions is essential. Here we present how to achieve selective topology manipulation, enabling one to get either a skyrmion state or a topologically trivial bubble state in a single specimen. The topology manipulation is governed by the magnetic singularity, i.e., Bloch point, of which injection can be controlled by sweeping a slight in-plane field that leads to intensive concentration of the local exchange energy. Based on the topology manipulation, we experimentally demonstrate the superior robustness of the topologically nontrivial skyrmion structure compared to the magnetic bubbles, which are topologically identical to a uniform state. Finally, we introduce other members of the skyrmion family, which share the similar topology-originated phenomena of conventional magnetic skyrmions, exploring the universal behaviors of topological spin textures in magnetic systems.