Magnetoelastic ‘‘gain’’ associated with saw propagation in magnetic garnet films

Abstract

The magnetic field dependence of the surface acoustic wave attenuation in magnetic garnet films has been experimentally investigated. SAW delay lines have been fabricated on magnetic garnet films. Aluminum interdigital transducers on piezoelectric layer (zinc-oxide film sputtered on top of the garnet film) have been used for acoustic wave generation and detection. The variation in the SAW attenuation as a function of a dc magnetic field applied in different in-plane and out-of-plane orientations has been investigated. One of the interesting observations we obtained was that at certain applied field range the SAW attenuation was found to be reduced below its zero-bias value. This negative change in attenuation or ‘‘gain’’ in the SAW signal motivated us to investigate different loss mechanisms associated with SAW propagation in magnetic films. The use of lossy garnet films helped reveal different loss mechanisms dominating in different magnetic field ranges.