| Since the birth of photonic crystals and phonon crystals, the artificialmicrostructure functional compound materials have brought manyconveniences in information technology of humanity’s life and the work. Asthe counterpart of photonic crystals or phonon crystals in the domain ofmagnetic materials, magnonic crystals have received much widespreadattentions of the scientific researchers in recent years. After photonic crystalsand phonon crystals, magnonic crystals are another kind of brand-newartificial microstructure function compound materials.Magnonic crystals are usually composed of two kinds or more magneticmaterials arranged periodically in the space. A prominent characteristic ofmagnonic crystals is the spin waves of frequencies localized in the gap cannot propagate through the whole composed system. Magnonic crystals withband gaps of spin waves have many potential applications in the microwavefield, and the research on the characteristics of the spin-wave band gaps is animportant research topic in the field of artificial composite materials.An important research direction is to obtain the expectation energy bandstructure with large gaps for the magnonic crystals with the nanometer size. Inthis thesis, the improved plane-wave expansion method by our research grouphas been used to calculate band structures of two-dimensional magnoniccrystals, and band gaps of two-dimensional magnonic crystals with cylinderand elliptic rods arranged as the rectangle and the square lattices areinvestigated, respectively. And then, the optimization of band gaps of thesystems with the elliptic cylinder scatterers is studied, and the results showthat band gaps can be optimized by rotating the elliptic rods.The numerical results of this thesis can provide some theoretical basis to the design of microwave devices made of magnonic crystals. |
