Title :
SAW measurements on a Nb film and an YBa2Cu3O 7 film
Author :
Baum, H.P. ; Sarma, B.K. ; Levy, M. ; Gavaler, J. ; Hohler, A.
Author_Institution :
Wisconsin Univ., Milwaukee, WI, USA
fDate :
3/1/1991 12:00:00 AM
Abstract :
Surface acoustic wave attenuation measurements have been performed in a screen room on a superconducting film of Nb at 659 MHz and on a high-Tc film of YBa2Cu3O7 at 168 MHz. The attenuation in the Nb film is due to electron-phonon interaction and follows a BCS (Bardeen-Cooper-Schrieffer) curve in the superconducting state. The measured change in attenuation was 0.8 dB/cm, giving an electron mean free path which is about twice as large as the value obtained from the sheet resistivity of the Nb film. The sheet resistivity of the YBa2Cu3O7 film was 45 Ω/□, and the observed change in attenuation at Tc =87 K was 0.18 dB/cm. A percolation model is proposed for describing the behavior of both the attenuation and the sheet resistivity in the superconducting state. This model is also used to determine the minimum resistance of YBa2Cu3O7 along the ab plane. It is found to be 12.5 μΩ-cm
Keywords :
barium compounds; high-temperature superconductors; niobium compounds; superconducting thin films; surface acoustic waves; surface conductivity; type II superconductors; yttrium compounds; 168 MHz; 659 MHz; BCS; Nb; YBa2Cu3O7 film; electron mean free path; electron-phonon interaction; high temperature superconductor; sheet resistivity; surface acoustic wave attenuation; Acoustic measurements; Acoustic waves; Attenuation measurement; Charge carrier processes; Conductivity; Electrons; Niobium; Performance evaluation; Superconducting films; Surface acoustic waves;
Journal_Title :
Magnetics, IEEE Transactions on
