From low to high Tc: An ultrasonic investigation of niobium single crystal and YBaCuO superconducting thin films with surface acoustic waves

Thesis/Dissertation · Mon Jan 01 04:00:00 EST 1990

OSTI ID:5901358

Baum, H

New results of surface acoustic waves (SAW) measurements on superconducting thin films from low critical temperature Tc (niobium, 8.6 K) to high Tc (Y1Ba2Cu3O(7-delta), 87 K) are reported. All films were less than 1 micron thick. The 700 MHz Rayleigh type SAW were used for the Nb investigation, whereas all other measurements were performed at 170 MHz. Critical findings about environmental, and internal, electromagnetic (e-m) noise are detailed, and those led to the initiation of a last study, the SAW attenuation in the substrate itself, under similar conditions. Some experiments reported were performed in a Faraday cage, to screen out all external e-m influences. This allowed for exceptional resolution (better than 0.01 dB) and for the discovery of small attenuation changes (0.2 dB) at the superconducting transition. A single crystal Nb film was studied and the results appear to follow the electron-phonon nature of the interaction of SAW with this type of superconductor. In Y1Ba2Cu3O(7-delta)(high Tc superconductor) however, the small change in attenuation observed at the transition is explained by the acousto-electric effect and the percolation theory. The direct measurements of ultrasonic surface wave attenuation on bare LiNbO3 substrates at 170 MHz appear to confirm results obtained elsewhere with a laser probe, and extend their range of validity down to 4 K. An example of potential application of the use of SAW with the new high Tc superconducting thin films, the Frequency Adjustable Surface Acoustic Wave device (FASAW) to be used as a tunable filter, chirp, encoder-decoder, and other, device is presented. Some ideas for new types of measurements of thin films and bulk material, with SAW are developed.

• Research Organization: Wisconsin Univ., Milwaukee, WI (USA)
• OSTI ID: 5901358
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
426001 -- Engineering-- Superconducting Devices & Circuits-- (1990-)
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CRYSTALS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRON-PHONON COUPLING
ELEMENTS
FILMS
HIGH-TC SUPERCONDUCTORS
METALS
MONOCRYSTALS
NIOBIUM
NOISE
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SOUND WAVES
SUPERCONDUCTING FILMS
SUPERCONDUCTIVITY
SUPERCONDUCTORS
THIN FILMS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
WAVE PROPAGATION
YTTRIUM COMPOUNDS
YTTRIUM OXIDES