Vortex dynamics in thin elliptic ferromagnetic nanodisks

• Дата: 2015
• Автор: Wysin, G.M.
• Формат: Стаття
• Мова: English
• Опубліковано: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2015
• Назва видання: Физика низких температур
• Теми: К 80-летию уравнения Ландау–Лифшица
• Онлайн доступ: http://dspace.nbuv.gov.ua/handle/123456789/128084
• Назва журналу: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Цитувати: 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