Observation of self-modulation spin-wave instability in a one-dimensional magnonic crystal

The emergence of the self-modulation instability of monochromatic microwave spin waves excited in a periodic magnetic film structure, a magnonic crystal, has been observed. The magnonic crystal was fabricated by chemically etching the surface a single-crystal yttrium-iron garnet film. The self-modulation instability has been observed at the frequencies corresponding to the band gaps of the spin-wave spectrum of the magnonic crystal caused by Bragg resonances. Above a certain threshold value of the input microwave signal, the time profile of the output pulses corresponds to envelope solitons.