Temperature dependence of spin wave auto-oscillations in Sc-substituted yttrium iron garnet films

Low frequency oscillations, often called auto-oscillations, are observed in the microwave power absorbed by ferrimagnetic oxides such as yttrium iron garnet (YIG). This report is concerned with the temperature dependence of frequency of auto-oscillations f_osc for parallel pumping in Sc-substituted YIG. Data on f_osc vs. the static field H were obtained for a 35 μm thick film for temperatures t ranging from 80 K to 300 K. For a specific t-value, f_osc vs. H data resemble the butterfly curve for parallel pumping. As t is decreased, auto-oscillations appear at low H-values and f_osc increases. Data on f_osc vs. t are compared with our recent theoretical model in which the t-dependence is assumed to arise mainly from variations in the spin wave group velocity and the interaction parameters. The model gives a very good qualitative description of the observed t-dependence of f_osc