Ultrasonic Characterization of High Tc and Other Unconventional Superconductors.
Abstract
Ultrasonic techniques have been used to characterize the properties of high Tc superconductors. A model is being developed to explain the radiation losses from a resonating fused silica sample. A new very sensitive resonant technique was developed for studying vortex motion in the superconducting state of an untwinned single crystal of YBCO. Evidence is obtained for a transition from a soft vortex system to a rigid strongly interacting vortex system in the vicinity of the superconducting transition temperature. A percolation model developed in our group to describe surface acoustic wave attenuation in a granular superconducting film was modified to include the resistivity of the individual grains in a matrix of Josephson junctions. SAW measurements using a pontoon technique on both a single crystal and a thin film of YBCO demonstrate the importance of pinning sites in determining the nature of a vortex transition; the vortex system will undergo a depinning transition if the pinning density is large and a melting transition if it is small. Resonant ultrasonic spectroscopy data obtained as a function of gas pressure has been analyzed.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1996
- Accession Number
- ADA307816
Entities
People
- Moises Levy
Organizations
- University of Wisconsin–Milwaukee