Vortex Dynamics in Magnetic Nanodisks With a Ring of Magnetic Defects

The dynamics of magnetic vortex in nanodisks with a ring-shaped magnetic defect is investigated using micromagnetic simulations. It is found that a spin-polarized current can drive the vortex core precession, and the presence of the ring affects the final steady oscillation radius R
_v
and the precession frequency f of the vortex core. Moreover, the precession frequency of the vortex core is sensitive to the size of the ring. In addition, compared with regular nanodisks, the oscillation frequency can be modulated in a wide range for a small exchange stiffness constant Ar of the ring. The ring-shaped defect paves a new pathway for regulating the frequency of magnetic vortex oscillators.