Vortex dynamics in magnetic nanodisks with a ring of magnetic defects

Recently, nanoscale ferromagnetic disk-shaped elements have aroused intensive investigation for their potential applications in numerous magnetoelectronic devices. In a magnetic nanodisk, the equilibrium between the exchange interaction and the magnetostatic energy leads to one special magnetization configuration, called magnetic vortex . Many theoretical and experimental researches have verified that the gyrotropic mode of the vortex core motion can be induced by the external field or spin polarized current, and then some works focused on investigating the precession frequency . It is well known that the oscillation frequency is one most important parameter for spin-transfer nano-oscillators (STNOs) based on vortex precession. Nowadays, great efforts have been devoted to study the effect of pointlike magnetic defects in the eigenfrequency of vortex core, however, the effect of ring-shaped magnetic defects in the precession frequency has not yet been detailed studied . In this paper, we inserted a ring of magnetic defects into magnetic nanodisk, and studied the dynamics of magnetic vortex by micromagnetic simulation.