R. Gaffney et al., SURFACE-ACOUSTIC-WAVE MEASUREMENTS OF YBA2CU3O7-DELTA THIN-FILMS AND SINGLE-CRYSTALS, Applied physics letters, 70(11), 1997, pp. 1468-1470
Surface acoustic wave (SAW) velocity and attenuation measurements have
been performed on high-temperature superconducting YBa2Cu3O7-delta (Y
BCO) thin films (deposited on nonpiezoelectric substrates), and YBCO s
ingle crystals, A ''bridge'' technique is employed in which piezoelect
ric substrates, patterned with interdigital transducers, are bonded to
the sample under investigation. The temperature dependence of 168 MHz
SAW attenuation in a single crystal near its superconducting transiti
on has been measured in applied magnetic fields up to 1.6 T. Features
are seen above the superconducting transition temperature which may be
indicative of a transition in the electric polarization of the materi
al. A. field-dependent attenuation peak, seen in the superconducting s
tate, is discussed in terms of the theory of thermally activated vorte
x motion. (C) 1997 American Institute of Physics.