Nonlinear magnetization dynamics under circularly polarized field

Exact analytical results are presented For the nonlinear large motion of th e magnetization vector in a body with uniaxial symmetry subject to a circul arly polarized held. The absence of chaos, the existence of pure time-harmo nic magnetization modes with no generation of higher-order harmonics, and t he existence of quasiperiodic magnetization modes with spontaneous breaking of the rotational symmetry are proven. Application to ferromagnetic resona nce and connection with the Stoner-Wohlfarth model are discussed. DOI: 10.1 103/PhysRevLett.86.724.