Eur. Phys. J. B 2, 177-182 (1998)
https://doi.org/10.1007/s100510050238

Anomalies of attenuation and phase velocity of surface acoustic waves in YBa₂Cu₃O_7-8 thin films in the vicinity of T_c

¹ Laboratoire de Physique des Solides, Université de Paris-Sud, 91405 Orsay Cedex, France
² Laboratoire LMDH, Université Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris Cedex 05, France
³ Unité Mixte de Physique CNRS/THOMSON, Domaine de Corbeville, 91404 Orsay Cedex, France

Corresponding author: ^a baumhoff@lps.u-psud.fr

Received: 7 August 1997
Revised: 7 November 1997
Accepted: 17 November 1997
Published online: 15 March 1998

Abstract

We present measurements of the attenuation and phase velocity of surface acoustic waves in thin YBa₂Cu₃O_7-8 films as a function of temperature, in magnetic fields up to 3.6 T applied parallel to the c-axis of the films. We have observed anomalies in both, the attenuation and the phase velocity in the vicinity of the superconducting critical temperature which do not depend on the magnetic field. Possible origins of these anomalies, observed, to our knowledge, for the first time in YBa₂Cu₃O_7-8 thin films, are discussed and compared to bulk acoustic wave experiments. We present a kind of feedback technique for surface acoustic waves which improves the sensitivity of this type of measurement. The actual sensitivity limits are mentioned.