HIGH TRANSITION-TEMPERATURE SUPERCONDUCTING SURFACE-ACOUSTIC-WAVE DEVICES

Thin films of high transition temperature superconducting YBa2Cu3O7-de lta (YBCO) have been deposited onto YZ-cut LiNbO3 and photolithographi cally patterned into surface acoustic wave (SAW) devices operating at 50 and 100 MHz center frequencies. Both devices show sharp improvement in SAW transduction efficiency as temperatures are lowered to the sup erconducting transition temperature of the YBCO electrodes. The magnit ude of the improvement is directly dependent on the normal state resis tance of the YBCO, and in one case was as high as 12 dB. In both cases , the amplitude change over the entire temperature range is matched ne arly exactly by the derived ideal electrode behavior predicted from th e aperture width, substrate radiation resistance, and YBCO electrode s heet resistance.