Proximity coupling of surface acoustic waves to a superconducting AlxO1-xfilm

We present the first preliminary results on proximity coupling of surface acoustic waves (SAW) to a superconducting AlxO1-xfilm. The aluminum film was evaporated onto a glass substrate in a partial pressure of oxygen. The glass was then placed, with the film face down, between a pair of SAW transducers on a piezoelectric LiNbO3substrate. Mechanical coupling between film and SAW was very weak and any attenuation of the SAW by electron-phonon interaction could be neglected. The SAW was attenuated by the coupling to the film of the piezoelectric field that the SAW produced. We found a large decrease in attenuation when superconductivity starts to appear in the film.