Mechanism of band gap formation in the spin-wave spectrum of coupled magnon crystals

The features of the propagation of spin waves in a layered periodic structure in the form of magnon crystals with a periodic system of grooves on the surface separated by an insulating layer are theoretically studied. The mechanism of band gap formation in the spectrum of spin waves in the structure under study is revealed. It is shown that one, two, three, or four band gaps can be formed near the first Bragg resonance. The positions of band gaps, their widths, and frequency interval between them are determined by the ratio of the geometric and magnetic parameters of the magnon crystals.