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Ultrasonic attenuation of surface acoustic waves in thin films of high transition temperature superconducting Nb/sub 3/Sn and NbN

Thesis/Dissertation ·
OSTI ID:5488186
The ultrasonic attenuation of 600-700 MHz surface acoustic waves by two high T/sub c/, cubic crystal structure, superconducting thin films has been investigated. The films studied were two, 0.5 ..mu.. thin, Nb/sub 3/Sn samples, electron-beam codeposited on LiNbO/sub 3/ and Quartz, and eleven NbN samples from 3 x 10/sup 3/ angstrom to less than or equal to 200 angstrom thin, sputter deposited on LiNbO/sub 3/. The Nb/sub 3/Sn (A15 structure) film on Quartz was difficult to measure due to defects in the Quartz caused by the high deposition temperature (approx. =700/sup 0/C) used to make the high T/sub c/ form of the compound. The Nb/sub 3/Sn film on LiNbO/sub 3/, however, provided information about the transition temperature and energy gap at T = 0 K when the attenuation was measured as a function of temperature in zero magnetic field. A theory is developed to predict the electron-phonon produced normal state attenuation of surface acoustic waves by a thin, loss producing film on a nonattenuating substrate. Using a viscous drag model for the attentuation, the predictions of the theory are compared to the measured normal state attenuation to find the electron mean-free-path for the Nb/sub 3/Sn film on LiNbO/sub 3/.
Research Organization:
Wisconsin Univ., Milwaukee (USA)
OSTI ID:
5488186
Country of Publication:
United States
Language:
English