Accession Number:

ADA214030

Title:

Bulk Wave Characterization of High Tc Superconductors

Descriptive Note:

Annual rept. 1 Nov 1988-1 Nov 1989

Corporate Author:

WISCONSIN UNIV-MILWAUKEE DEPT OF PHYSICS

Personal Author(s):

Report Date:

1989-11-01

Pagination or Media Count:

11.0

Abstract:

The objective of this research is to characterize high Tc superconductors with ultrasonic waves. A peak in ultrasonic attenuation has been observed at the superconducting phase transition of the thalium superconducting compound with a Tc 103 K. The position of this peak is independent of frequency and therefore should not be produced by a relaxation mechanism. It may be produced by interactions with fluctuations associated with the superconducting phase transition. The magnitude of the peak decreases in magnetic fields up to 6 Tesla. This appears to be the first time that an attenuation effect has been observed which is directly associated with the superconducting state of a high Tc superconductor. Shear waves propagating parallel to the Copper Oxide planes and polarized in the CuO planes of a sinter forged YBa2Cu3O7 sample exhibit only one maximum in attenuation at around 180 K. Velocity measurements in the copper free high Tc superconductors Ba1-xKx BiO3 show a definite change in slope at the phase transition. Measurements in the heavy Fermion superconductor UPt3 show a 40 ppm change in velocity around 4.5 K, its antiferromagnetic phase transition temperature.

Subject Categories:

  • Electricity and Magnetism

Distribution Statement:

APPROVED FOR PUBLIC RELEASE