High power microwave properties of Zn-Y hexagonal ferrite

Summary form only given. High anisotropy hexagonal ferrite materials offer advantages for millimeter wave device applications. Implementation often involves a quantitative understanding of the high power response and the related spin wave linewidth /spl Delta/H/sub k/. Recent high power measurements on disks of single crystal easy plane Y-type hexagonal ferrite at 9 GHz gave parallel pump and subsidiary absorption /spl Delta/H/sub k/ values which were a factor of two or more larger expected from low power ferromagnetic resonance (FMR) and high power resonance saturation data. New measurements show that the sample size has a significant effect on the instability threshold and the corresponding /spl Delta/H/sub k/, especially at low frequency when the intrinsic /spl Delta/H/sub k/ is small. Sample shape is not critical at higher frequencies where /spl Delta/H/sub k/ is large.