THE EXCITATION OF MAGNETOACOUSTIC WAVES AT MICROWAVE FREQUENCIES.
Final rept., 1 Nov 65-31 Oct 66,
SPERRY RAND RESEARCH CENTER SUDBURY MASS
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The theoretical instability thresholds are derived for both degenerate and nondegenerate processes involving transversely pumped magnetoelastic shear waves. The results indicate that for equal spin wave and elastic Qs quality factor the magnetoelastic instabilities have higher thresholds than the Suhl instability everywhere within the sample. The experimental observations are in qualitative agreement with this theory only for very small angles between the magnetic field and the direction of propagation of the magnetoelastic waves. Optical-contact bonds have been made between various materials. These bonds were found to be superior to other types of bonds transmitting L-band shear and longitudinal elastic waves. By bonding YAG disks of appropriate thickness to the ends of an axially magnetized YIG rod, the sense of circular polarization of magnetoelastic waves has been reversed so that low-loss propagation through the entire rod was possible. This method allows one to construct variable delay lines that operate in a transmission mode rather than in a reflection mode. It also isolates the pump from the output end of the rod. Author