Analysis of quasiperiodic Landau-Lifshitz-Gilbert dynamics

We study magnetization dynamics in a uniformly magnetized uniaxial film or particle, subject to a circularly polarized field by using Landau-Lifshitz-Gilbert equation. Rotational invariance of the system around the symmetry axis permits one to reduce the problem to the study of an autonomous dynamical system on the unit sphere. Quasiperiodic magnetization dynamics correspond to limit cycles of this reduced dynamical system. The existence, the number and the position of limit cycles are studied through the Melnikov function approach. (C) 2003 Elsevier B.V. All rights reserved.