Modulation of magnonic band structure via wall width variations in 1D magnonic crystals

Magnonic crystals are artificial periodic structures that enable control over spin-wave propagation by introducing bandgaps in the magnonic band structure. In this study, we systematically investigate how the wall-to-valley width ratio affects the magnonic band structure in one-dimensional magnonic crystals. Micromagnetic simulations demonstrate that as the wall width increases, the bandgap frequencies shift higher due to an increase in the effective film thickness. Additionally, the bandgap width exhibits an oscillatory dependence on the wall-to-valley ratio. These behaviors are attributed to changes in the effective film thickness of entire MC and the local wavelength matching to the wall and valley length. Furthermore, we developed a Kronig-Penney model incorporating the spin-wave dispersion relation, which reasonably reproduces the band structure observed in micromagnetic simulations. This framework provides a fundamental basis for designing magnonic band structures with tailored properties. Our findings highlight the tunability of magnonic band structures via structural modulation, offering potential applications in spin-wave-based computing and magnonic logic devices.