Lower bound on the eigenvalues of the characteristic equation for an arbitrary multilayered gyromagnetic structure with perpendicular magnetization

A layered gyromagnetic waveguiding structure magnetized perpendicularly to interfaces between layers is analyzed. The lower bound on the eigenvalues of the wave equation for this structure is derived using the spectral theory of linear operators. The elements of the transfer matrix for a layer of a gyromagnetic medium are given. A numerical example confirming the validity of the theoretical results is included.<
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