Localized states beyond the asymptotic parametrically driven amplitude equation

We study theoretically a family of localized states which asymptotically connect a uniform oscillatory state in the magnetization of an easy-plane ferromagnetic spin chain when an oscillatory magnetic field is applied and in a parametrically driven damped pendula chain. The conventional approach to these systems, the parametrically driven damped nonlinear Schrödinger equation, does not account for these states. Adding higher order terms to this model we were able to obtain these localized structures.