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Magnon modes and magnon-vortex scattering in two-dimensional easy-plane ferromagnets

B. A. Ivanov·H. J. Schnitzer·F. G. Mertens·G. M. Wysin
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Abstract

We calculate the magnon modes in the presence of a vortex in a circular system, combining analytical calculations in the continuum limit with a numerical diagonalization of the discrete system. The magnon modes are expressed by the S-matrix for magnon-vortex scattering, as a function of the parameters and the size of the system and for different boundary conditions. Certain quasi-local translational modes are identified with the frequencies which appear in the trajectory X(t) of the vortex center in recent Molecular Dynamics simulations of the full many-spin model. Using these quasi-local modes we calculate the two parameters of a 3rd-order quation of motion for X(t). This equation was recently derived by a collective variable theory and describes very well the trajectories observed in the simulations. Both parameters, the vortex mass and a factor on the third time derivative of X(t), depend strongly on the boundary conditions.

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B. A. Ivanov, H. J. Schnitzer, F. G. Mertens, G. M. Wysin. 1998-05-14. Magnon modes and magnon-vortex scattering in two-dimensional easy-plane ferromagnets. https://doi.org/10.1103/physrevb.58.8464

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