Vortex dynamics in thin elliptic ferromagnetic nanodisks

• Published in: Физика низких температур
• Date: 2015
• Main Author: Wysin, G.M.
• Format: Article
• Language: English
• Published: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2015
• Subjects: К 80-летию уравнения Ландау–Лифшица
• Online Access: https://nasplib.isofts.kiev.ua/handle/123456789/128084
• Journal Title: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Cite this: Vortex dynamics in thin elliptic ferromagnetic nanodisks / G.M. Wysin // Физика низких температур. — 2015. — Т. 41, № 10. — С. 1009–1023. — Бібліогр.: 34 назв. — англ.

Vortex gyrotropic motion in thin ferromagnetic nanodisks of elliptical shape is described here for a pure vortex
 state and for a situation with thermal fluctuations. The system is analyzed using numerical simulations of the
 Landau–Lifshitz–Gilbert (LLG) equations, including the demagnetization field calculated with a Green's function
 approach for thin film problems. At finite temperature the thermalized dynamics is found using a second order
 Heun algorithm for a magnetic Langevin equation based on the LLG equations. The vortex state is stable only
 within a limited range of ellipticity, outside of which a quasi-single-domain becomes the prefered minimum
 energy state. A vortex is found to move in an elliptical potential, whose force constants along the principal axes
 are determined numerically. The eccentricity of vortex motion is directly related to the force constants. Elliptical
 vortex motion is produced spontaneously by thermal fluctuations. The vortex position and velocity distributions
 in thermal equilibrium are Boltzmann distributions. The results show that vortex motion in elliptical disks can be
 described by a Thiele equation