Magnetic excitations of skyrmions in antiferromagnetic-exchange coupled disks

Abstract

Magnetic skyrmions are topologically protected spin textures. They can exist in bilayer synthetic antiferromagnets and have some exotic behaviors in terms of dynamics. In this work, we theoretically studied the dynamics of magnetic skyrmions in antiferromagnetic-exchange coupled disks in terms of microwave response using micromagnetic simulations. It is well known that clockwise (CW)/counterclockwise (CCW) circular resonance modes of skyrmions can be excited when an in-plane microwave is applied to the system. We found three coupled excitation modes (CW-CW, CCW-CCW, and CW-CCW) in the presence of antiferromagnetic-exchange coupling and the type of excitation mode depends on the frequency of the in-plane microwave. Furthermore, the topological trajectories of excitation modes are elliptical. For the low frequency (less than 10 GHz) excitation, the trajectory is close to linear mode since the major axis of the ellipse is much larger than its minor axis.