Comparison of effective linewidth and FMR linewidth at 10 GHz in Ho substituted YIG

The effective linewidth and FMR (ferromagnetic resonance) linewidth techniques were applied at 10 GHz and room temperature to rare-earth holmium-substituted yttrium-iron-garnet (HoYIG) spheres. Linewidths were determined for HoYIG spheres with varying amounts of substituted Ho. The FMR linewidth and effective linewidth measured for the HoYIG samples ranged from 4 to 240 Oe. The measured linewidths from the different techniques were compared to determine the sensitivity of the effective linewidth technique to various loss mechanisms over a wide field range. It is found that the linewidths determined from the different techniques track closely. The high field effective linewidth agrees with the measured FMR linewidth for all but the smallest Ho substitution