THICKNESS AND TEMPERATURE-DEPENDENCE OF SUBSIDIARY ABSORPTION THRESHOLDS IN YTTRIUM-IRON-GARNET THIN-FILMS

The microwave subsidiary absorption threshold in tangentially magnetiz ed yttrium-iron-garnet (YIG) films was measured as a function of the s tatic magnetic field, film thickness and temperature. A large decrease in the high field limit of the butterfly curve with a thickness decre ase in the 0.3-3 mum range is observed. The effect is explained quanti tatively by using modified Damon-Eshbach dispersion relations which ta ke into account exchange interactions. The effect of temperature on h( crit) the smallest threshold field amplitude, in the 250 < T < 450 K t emperature range can be expressed by an empirical relationship h(crit) is-proportional-to M(s)(T)-1.6 where M(s) is the saturation magnetiza tion. This h(crit) vs M(s) relationship is similar to that obtained fo r the magnetization dependence of parallel pump thresholds in Li-Ti fe rrite compounds.