The impact of the lattice symmetry and the inclusion shape on the spectrum of 2D magnonic crystals

We investigate spin waves in two-dimensional superlattices in the form of an infinite ferromagnetic slab of finite thickness with periodically embedded ferromagnetic inclusions. One of the reasons of the interest in magnonic superlattices is the possibility of tailoring their spectrum to produce magnonic gaps, crucial for the prospective applications. The objective of this study is to find the optimal values of structural parameters for which low-frequency magnonic gaps will occur and have a maximum width. We provide some guidelines for designing superlattices with a desired spectrum. We focus on the role of the symmetry of the lattice versus other geometrical factors, including the filling fraction and the superlattice constant. We compare the spectra of superlattices with inclusions of circular, hexagonal, and square cross sections.