Vortex Core Switching Dynamics in Submicron Permalloy Disk

The switching dynamics of the magnetic vortex core in a submicrometer-scale Permalloy disk is investigated by micromagnetic modeling. At zero magnetic field, the vortex state is formed with a single vortex core at the disk center. When an in-plane magnetic field pulse with an appropriate strength and duration is applied to the vortex structure, an additional two vortices, i.e., a vortex and an anti-vortex, with an opposite polarity are created near the original vortex core. Subsequently, the original vortex core annihilates with the antivortex core, and the final magnetic state contains a single core with the reversed polarity. The dynamics of the vortex core switching are discussed in terms of the nonlocal torque exerted to spins in response to an externally applied magnetic field pulse