Issue Eur. Phys. J. B Volume 25, Number 1, January I 2002 Page(s) 89 - 100 Section Statistical and Nonlinear Physics DOI 10.1140/e10051-002-0010-1

Eur. Phys. J. B 25, 89-100 (2002)
DOI: 10.1140/e10051-002-0010-1

Scattering of vortex pairs in 2D easy-plane ferromagnets

A.S. Kovalev¹, S. Komineas² and F.G. Mertens<sup>2

1</sup>  Institute for Low Temperature Physics and Engineering, 47 Lenin Ave., 61164 Kharkov, Ukraine
²  Physikalisches Institut, Universität Bayreuth, 95440 Bayreuth, Germany

stavros.komineas@uni-bayreuth.de

(Received 18 September 2001)

Abstract
Vortex-antivortex pairs in 2D easy-plane ferromagnets have characteristics of solitons in two dimensions. We investigate numerically and analytically the dynamics of such vortex pairs. In particular we simulate numerically the head-on collision of two pairs with different velocities for a wide range of the total linear momentum of the system. If the momentum difference of the two pairs is small, the vortices exchange partners, scatter at an angle depending on this difference, and form two new identical pairs. If it is large, the pairs pass through each other without losing their identity. We also study head-tail collisions. Two identical pairs moving in the same direction are bound into a moving quadrupole in which the two vortices as well as the two antivortices rotate around each other. We study the scattering processes also analytically in the frame of a collective variable theory, where the equations of motion for a system of four vortices constitute an integrable system. The features of the different collision scenarios are fully reproduced by the theory. We finally compare some aspects of the present soliton scattering with the corresponding situation in one dimension.

PACS
75.10.Hk - Classical spin models.
75.70.Kw - Domain structure (including magnetic bubbles).
05.45.Yv - Solitons .


© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2002

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