Dispersion Characteristics of Spin Waves in a Nanoscale Magnon Crystal

The paper presents the results of a study of the features of spin-wave propagation in a magnon crystal based on a nanoscale ferromagnetic film with a periodic system of grooves on its surface. Micromagnetic modeling was conducted in the MuMax3 environment. It is found that additional hybrid modes form on the dispersion curve of the magnon crystal near each fundamental width mode. The ratio of the ridges-to-grooves width influences the energy distribution among hybrid modes and the cut-off frequency of the fundamental modes. The impact of the ridges-to-grooves width ratio on the formation of forbidden zones based on dispersion and amplitude-frequency characteristics is analyzed. It is shown that the most pronounced forbidden zones occur for larger ridges-to-grooves width ratios. Additionally, increasing the ridges-to-grooves width ratio and deepening the grooves increases the number of expressed Bragg resonance orders.