A simple phenomenological model has been developed that is useful for the approximate design of tunable SAW devices using magnetostrictive thin films. The model formulation, based on perturbation theory, relates the maximum magnetic-field dependent velocity change or tunability range to the frequency of operation, film thickness, elastic properties of the film and substrate, and magnetic properties of the film. Iron-terbium-boron films deposited on quartz and lithium niobate substrates were used to verify the formula. A significant variability in the magnetic properties of the films were obtained by varying the amount of terbium (0-5 atomic percent) in the film (80 percent Fe and 15-20 percent B). Other films including Fe-Tb, Fe-Si, Fe-B, Co-Cr, and Ni, which were studied by other investigators, were also used to check the model. A simple figure of merit for comparing various film-substrate combinations, independent of device dimensions was also derived and experimentally checked.
|Original language||English (US)|
|Number of pages||5|
|Journal||IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control|
|State||Published - Nov 1988|