Nonlinear dynamics of the magnet with localized high-frequency external impact

The stability of quasi-soliton excitations localized in a magnet near the region of excitation by a high-frequency external field has been studied within the framework of two models. They include nonlinear regions strongly excited by external pumping and regions of subsystems interacting with them, considered in the linear approximation. In the first model, the linear region is considered in the long-wavelength approximation for a system of finite length with distributed parameters. The second model considers a finite-dimensional system of coupled two linear and nonlinear magnetic moments under point pumping conditions. The similarity of the results of the two models is demonstrated. The existence of two regions of instability is shown: exponential and oscillatory, and their parameters are calculated. In both cases, the transition to the nonlinear regime of instability is accompanied by the formation of a train of nonlinear excitations of the type of “temporary” solitons of different nature. The nonlinear evolution of the instability leads to the transition of the system to a new stable state in the case of exponential instability, and the state of a stable limit cycle in the region of oscillatory instability.