Parametric frequency conversion with amplification of a weak spin wave in a ferrite film

We report on experiments of parametric frequency conversion of a weak signal spin wave by a copropagating strong pump spin wave. An effective spin-wave frequency conversion with amplification occurred when the carrier frequencies of the co-propagating waves were in the spectral region of high negative dispersion in the dipole-exchange spin-wave spectrum of the film. A theoretical explanation of the observed phenomenon is given in terms of a four-wave parametric interaction process