Vortex polarity switching in magnets with surface anisotropy

• Published in: Физика низких температур
• Date: 2015
• Main Authors: Pylypovskyi, O.V., Sheka, D.D., Kravchuk, V.P., Gaididei, Y.
• Format: Article
• Language: English
• Published: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2015
• Subjects: К 70-летию со дня рождения В. М. Локтева
• Online Access: https://nasplib.isofts.kiev.ua/handle/123456789/122071
• Journal Title: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Cite this: Vortex polarity switching in magnets with surface anisotropy / O.V. Pylypovskyi, D.D. Sheka, V.P. Kravchuk, Y. Gaididei // Физика низких температур. — 2015. — Т. 41, № 5. — С. 466-481. — Бібліогр.: 74 назв. — англ.

Vortex core reversal in magnetic particle is essentially influenced by a surface anisotropy. Under the action of a perpendicular static magnetic field the vortex core undergoes a shape deformation of pillow- or barrel-shaped type, depending on the type of the surface anisotropy. This deformation plays a key point in the switching mechanism: We predict that the vortex polarity switching is accompanied (i) by a linear singularity in case of Heisenberg magnet with bulk anisotropy only and (ii) by a point singularities in case of surface anisotropy or exchange anisotropy. We study in details the switching process using spin-lattice simulations and propose a simple analytical description using a wired core model, which provides an adequate description of the Bloch point statics, its dynamics and the Bloch point mediated switching process. Our analytical predictions are confirmed by spin-lattice simulations for Heisenberg magnet and micromagnetic simulations for nanomagnet with account of a dipolar interaction.