Dynamics of Magnetic Skyrmion Clusters Driven by Spin-Polarized Current With a Spatially Varied Polarization

Magnetic skyrmions are promising candidates for future information technology. We present a micromagnetic study of isolated skyrmions and skyrmion clusters in ferromagnetic nanodisks driven by a spin-polarized current with spatially varied polarization. The current-driven skyrmion clusters can be either dynamically steady or static, depending on the spatially varied polarization profile. For the dynamically steady state, the skyrmion cluster moves in a circle in the nanodisk, whereas for the static state, the skyrmion cluster is stationary. The frequency of the skyrmion circular motion and the dependence of skyrmion cluster dynamics on the magnetic anisotropy and Dzyaloshinskii-Moriya interaction are investigated. Our results may provide a pathway to realize devices based on magnetic skyrmion clusters.