4-MAGNON DECAY OF MAGNETOSTATIC SURFACE-WAVES IN YTTRIUM-IRON-GARNET FILMS

The four-magnon instability of magnetostatic surface waves (MSSWs) in yttrium iron garnet epitaxial films is investigated experimentally. It is shown that four-magnon instability fur MSSWs with wave numbers 30- 600 cm(-1) is a decay instability and develops for values of the wave magnetization close to the threshold level for second-order parametric instability of a homogeneous transverse pump wave. When the supercrit icality of the MSSW power is 15-20 dB, the generated parametric spin w aves themselves become unstable with respect to the four-magnon intera ction, so that kinetic instability develops in the film. It is shown t hat the pump signal transmitted through the signal and the length of t he ''nonlinear'' part of the film, where a MSSW is capable of exciting parametric spin waves, increase as the pump power is increased. (C) 1 997 American Institute of Physics.