Low Temperature Physics: 41, 361 (2015); https://doi.org/10.1063/1.4919374
Fizika Nizkikh Temperatur: Volume 41, Number 5 (May 2015), p. 466-481    ( to contents , go back )

Vortex polarity switching in magnets with surface anisotropy

Oleksandr V. Pylypovskyi and Denis D. Sheka

Taras Shevchenko National University of Kyiv, Kyiv 01601, Ukraine
E-mail: engraver@univ.net.ua

Volodymyr P. Kravchuk and Yuri Gaididei

Bogolyubov Institute for Theoretical Physics of NAS of Ukraine, Kyiv 03680, Ukraine
pos Анотація:

Received January 21, 2015

Abstract

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.

PACS: 75.10.Hk Classical spin models;
PACS: 05.45.–a Nonlinear dynamics and chaos;
PACS: 75.70.Rf Surface magnetism;
PACS: 75.75.–c Magnetic properties of nanostructures;
PACS: 75.78.–n Magnetization dynamics.

Key words: vortex core, surface anisotropy, magnetic field, Heisenberg magnet.

Published online: March 23, 2015

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