Pinning and movement of individual nanoscale magnetic skyrmions via defects

An understanding of the pinning of magnetic skyrmions to defects is crucial for the development of future spintronic applications. While pinning is desirable for a precise positioning of magnetic skyrmions it is detrimental when they are to be moved through a material. We use scanning tunneling microscopy (STM) to study the interaction between atomic scale defects and magnetic skyrmions that are only a few nanometers in diameter. The studied pinning centers range from single atom inlayer defects and adatoms to clusters adsorbed on the surface of our model system. We find very different pinning strengths and identify preferred positions of the skyrmion. The interaction between a cluster and a skyrmion can be sufficiently strong for the skyrmion to follow when the cluster is moved across the surface by lateral manipulation with the STM tip.