Parametric amplification of spin wave envelope solitons in ferromagnetic films by parallel pumping

A theory for parametric amplification of spin wave envelope solitons in ferromagnetic film by parallel pumping is suggested. A system of nonlinear equations describing evolution of nonlinear wave packets both in time and space domains is derived. Analysis shows that an effective amplification of spin wave solitons is possible in a transient regime when amplitudes of the parametrically excited waves are in growth. Numerical estimations of the experimental parameters necessary to achieve amplification of backward volume wave solitons in yttrium iron garnet films are given