Manipulation of Skyrmion by Magnetic Field Gradients: A Stern-Gerlach-Like Experiment.

Magnetic skyrmions are real-space topological spin textures, which have attracted increasing attention from the nanospintronics community. Toward functional skyrmionics, the efficient manipulation of skyrmions is a prerequisite, which has been successfully demonstrated through electrical, thermal, optical, and other means. Here, through integrating an interfacially asymmetric Ta/CoFeB/MgO multilayer with an on-chip wire that induces Oersted fields and their gradients, we show experimentally the generation and topology-dependent motion of Néel type skyrmions at room temperature. In particular, an opposite longitudinal motion for skyrmions with opposite topological charges along the gradient direction is observed. Through comparing with the well-known Stern-Gerlach experiment, in which the splitting of atomic spins under magnetic field gradients was observed, our work identifies another interesting aspect of the topological character of skyrmions. The present study could also be implemented for designing novel on-chip skyrmionic devices in which the manipulation of skyrmions cannot be done by electrical means.