Effect of Surface Polishing on the Linewidth and High-Power Properties of Single-Crystal Spheres of ZnY

Single-crystal (ZnY) (Ba2Zn2Fe12O22) was used in an investigation of the effects of surface finish on the linewidth and high-power properties. Measurements indicate that by polishing rough-ground spheres with successively finer grit abrasives, the linewidth can be reduced from 50 to 13.8 Oe. From the measured threshold field, the spin-wave linewidth (ΔHK) of 6.6 Oe has been calculated, in good agreement with that obtained by Green and Healy who used the parallel pump technique. Experiments indicate a threshold field an order-of-magnitude lower than for yttrium iron garnet with a comparable linewidth.