Surface acoustic-wave investigation of amorphous and granular superconducting films

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:6163974

Schmidt, J D

Measurements of the ultrasonic attenuation of 600-700 MHz surface acoustic waves and the dc resistance as a function of temperature were made on amorphous and granular superconducting films. A total of sixteen films were investigated which consisted of two different types of materials; Pb/PbO/sub x/ (granular) and In/InO/sub x/ (granular and amorphous). It is found that in both the amorphous and granular films, the ultrasonic attenuation is being produced by a mechanisms known as the acousto-electric effect rather than by the electron-phonon interaction. Although the attenuation mechanisms is the same in both types of films, the mechanisms by which the granular films enter the super-conducting state is found to be different from that for the amorphous films. In the granular films, the transition to the superconducting state occurs by means of a percolation process in which neighboring grains are randomly connected via Josephson tunneling. In the amorphous films, the transition to the superconducting state occurs by means of a Kosterlitz-Thouless transition in which free magnetic vortices combine to form bound pairs.

• Research Organization: Wisconsin Univ., Milwaukee (USA)
• OSTI ID: 6163974
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
ACOUSTIC TESTING
AMORPHOUS STATE
ATTENUATION
CHALCOGENIDES
ELEMENTS
FILMS
FREQUENCY RANGE
GRANULAR MATERIALS
INDIUM
INDIUM COMPOUNDS
INDIUM OXIDES
LEAD
LEAD COMPOUNDS
LEAD OXIDES
MATERIALS
MATERIALS TESTING
METALS
MHZ RANGE
MHZ RANGE 100-1000
NONDESTRUCTIVE TESTING
OXIDES
OXYGEN COMPOUNDS
SOUND WAVES
SUPERCONDUCTING FILMS
SURFACES
TESTING
ULTRASONIC TESTING
ULTRASONIC WAVES