Magnon band structure and magnon density in one-dimensional magnonic crystals

By using Callen's Green's function method and the Tyablikov and Anderson-Callen decoupling approximations, we systematically study the magnon band structure and magnon density perpendicular to the super lattice plane of one-dimensional magnonic crystals, with a superlattice consisting of two magnetic layers with ferromagnetic (FM) or antiferromagnetic (AFM) interlayer exchange coupling. The effects of temperature, interlayer coupling, anisotropy and external magnetic held On the magnon-energy band and magnon density in the K-x-direction are investigated in three situations: a) the magnon band of magnetic superlattices with FM interlayer coupling, b) separate and c) overlapping magnon bands of magnetic superlattices with AFM interlayer coupling. In the present work, a quantum approach is developed to study the magnon band structure and magnon density of magnonic crystals and the results are beneficial for the design of magnonic-crystal waveguides or gigahertz-range spin-wave filters. (C) 2014 Elsevier B.V. All rights reserved.