RF and microwave applications to SAW propagation in magnetic films

Surface acoustic wave (SAW) propagation in magnetic films can be implemented in different applications in the RF and microwave frequency ranges. Two applications based on the magnetoelastic interaction between the SAW and the magnetic spin system are discussed. First, the change in the phase velocity of the SAW was used in tuning RF delay-line based oscillators. The SAW delay lines are fabricated using ZnO layers on magnetic garnet films and operate at around 100 MHz. Second, the presence of the SAW slightly modulates the characteristics of the magnetic medium. Based on this effect, the scattering of magnetostatic waves (MSWs) by the acoustic waves was demonstrated. Both the MSW and the SAW are excited in the same garnet film. Yttrium-iron-garnet (YIG) films have been used to study the interaction between the SAW and MSW. Magnetostatic forward volume waves (MSFVWs) are employed. They are generated and detected using short-circuited microstrip lines on a dielectric substrate (ε_r=10.6). The SAWs are excited and detected using bulk acoustic wave transducers and a pair of Plexiglas wedges. Experimental results demonstrating the diffraction of magnetostatic waves by SAWs are reported. Different applications including microwave frequency identification and shifting using the scattering of MSWs by SAWs are discussed