Vortex motion in a finite-size easy-plane ferromagnet and application to a nanodot

Abstract

We study the motion of a non-planar vortex in a circular easy-plane ferromagnet, which imitates a magnetic nanodot. Analysis was done using numerical simulations and a new collective variable theory which includes the coupling of Goldstone-like mode with the vortex center. Without magnetic field the vortex follows a spiral orbit which we calculate. When a rotating in-plane magnetic field is included, the vortex tends to a stable limit cycle which exists in a significant range of field amplitude B and frequency $\omega$ for a given system size L. For a fixed $\omega$, the radius R of the orbital motion is proportional to L while the orbital frequency $\Omega$ varies as 1/L and is significantly smaller than $\omega$. Since the limit cycle is caused by the interplay between the magnetization and the vortex motion, the internal mode is essential in the collective variable theory which then gives the correct estimate and dependency for the orbit radius $R\sim BL/\omega$. Using this simple theory we indicate how an ac magnetic field can be used to control vortices observed in real magnetic nanodots.

15 pages (RevTeX), 14 figures (eps)

References in corpus (8)

• Imaging of Spin Dynamics in Closure Domain and Vortex Structures
• Magnon modes and magnon-vortex scattering in two-dimensional easy-plane ferromagnets
• Magnon modes for thin circular vortex state magnetic dot
• Internal Modes and Magnon Scattering on Topological Solitons in 2d Easy-Axis Ferromagnets
• Resonances in the dynamics of ${\varphi }^4$ kinks perturbed by ac forces
• Anomalous resonance phenomena of solitary waves with internal modes
• Switching between different vortex states in 2-dimensional easy-plane magnets due to an ac magnetic field
• Finite temperature dynamics of vortices in the two dimensional anisotropic Heisenberg model

Cited by in corpus (6)

• Controlled vortex core switching in a magnetic nanodisk by a rotating field
• Switching phenomena in magnetic vortex dynamics
• Dynamics of topological solitons in two-dimensional ferromagnets
• Viscous dynamics of vortices in a ferromagnetic film
• Precessing vortices and antivortices in ferromagnetic elements
• Field momentum and gyroscopic dynamics of classical systems with topological defects