Parametric magnon–phonon instability in the structure of YIG films

Abstract

The effects of parametric magnon–phonon instability and the self-modulation of magnetostatic and fast magnetoelastic waves are revealed. It is found that instabilities are caused by the decay of the initial waves stimulated by high-Q acoustic resonances. Decays of the first and the second order (three- and four-magnon–phonon decays) are observed. Their characteristics and existing conditions are determined. Magnetostatic wave decays have both upper and lower thresholds. It is shown that magnetoelastic waves become stable above the upper thresholds. The existence of the upper threshold is due to several competing decay scenarios.