Ferrite Materials for Advanced Multifunction Microwave Systems Applications

ONR Grant N00014-03-1-0070 has supported a research program with a focus on new materials for applications in the 6-18 GHz range relevant to the AMRFS (Advanced Multifunctional RF systems) Navy program. The program has emphasized three dates of materials, yttrium iron garnet (YIG) and compositional variants, lithium ferrites and compositional variants, and hexagonal ferrites. Polycrystalline and single crystal materials in bulk and thin film form were investigated. These materials were produced by a variety of techniques, including traditional sintering, hot isostatic pressing (HIPPING), liquid phase epitaxy, and pulsed laser deposition. Most materials were obtained as part of collaborations with other university, government, or industrial groups. The pulsed laser deposition thin film work on barium and lithium ferrite was done in-house. Specific measurements included the ferromagnetic resonance linewidth, the high field effective linewidth, the low field effective linewidth, the in-manifold effective linewidth, the spin wave instability threshold microwave field amplitude, and the associated spin wave linewidth. As appropriate for the specific measurement and the sample of interest, data were obtained as a function of frequency, temperature, static and microwave field configuration, and orientation. Time and apace resolved Brillouin light scattering and inductive magnetodynamic probe mapping were also used in this work.