Characteristics And Applications Of Line Defect Modes In Two-dimensional Magnonic Crystals

Artificial magnonic crystal is composed of two (or more) periodicmagnetic materials arranged in space, and it has been focused extensively onthe artificial microstructure composite material. The defect structure in crystalis the distortion of periodic potential field in lattice. Because of the existenceof defects, the crystal shows a variety of properties, and it is possible to makematerial processing and applications to be controlled and improved.Currently, there is still a blank area in the research field of magnoniccrystals composite materials, especially for the properties of defect states intwo-or three-dimensional Magnonic crystals especially for the properties ofdefect states in two-or three-dimensional Magnonic crystals. So, in thisdissertation, line defects of two-dimensional magnonic crystals are considered,and band structures of spin waves in the systems are numerically calculatedbased on the microscopic mechanism dominating the dispersion of spin wavesin magnetic materials.In this thesis, using the plane-wave expansion method under supercellapproximation, band structures of spin waves propagating in two-dimensionalmagnetic crystals composed of ferromagnetic materials Fe of squarearrangement in Euo and magnetization field distributions of some defect modes are calculated and compared. The obtained numerical results show thatthe guided band called line defect modes will presented in the band gap ofmagnonic crystals with line defect structures, and this defect mode canpropagate along the direction of the line defect. The magnonic crystals withline defect structures can be used as the fabricating materials of spin-wavewaveguide devices.