MAGNETOSTATIC WAVE DYNAMIC MAGNETIZATION RESPONSE IN YTTRIUM-IRON-GARNET FILMS

The dynamic microwave magnetization (DMM) amplitude of magnetostatic w aves in yttrium iron garnet films at 5-6 GHz has been measured as a fu nction of input power. The measurement is based on the characteristic frequency shift in the power transmission spectrum. This shift is rela ted to the reduction of the effective static magnetization and, theref ore, the increase of the DMM amplitude at high power. The measurements were made on 7.2-mu m-thick, single-crystal yttrium iron garnet films . A pulsed frequency-swept microwave signal at 5-6 GHz was used to lau nch the magnetostatic waves. The signals were excited and detected by planar microstrip transducers. Measurements were made for magnetostati c forward volume waves (MSFVW) and magnetostatic surface waves (MSSW). The duty cycle of the pulsed microwave signal was kept at 0.1% in ord er to avoid sample heating effects. The shifts for small features in t he transmission vs frequency profiles were used to determine the DMM a mplitudes. At low power, the DMM amplitude increased with power. Satur ation occurred at high power. The results indicate a saturation DMM re sponse at about 10% of the saturation magnetization for input power in the 3-4 W range for MSFVW signals and above 0.5 W for MSSW signals. ( C) 1996 American Institute of Physics.