Surface acoustic wave determination of the superconducting fraction of a Nb/sub 3/Ge film

Journal Article · Sun Aug 01 04:00:00 EDT 1982 · J. Low Temp. Phys.; (United States)

DOI:https://doi.org/10.1007/BF00681570· OSTI ID:6724203

Salvo, H Jr; Fredricksen, H P; Levy, M; Gavaler, J

Surface acoustic waves 1200 MHz were used to investigate the properties of a 0.5-..mu..m-thick film of Nb/sub 3/Ge. This film was rf-sputtered onto a substrate consisting of a piezoelectrically active 3.5-..mu..m AlN layer which was chemically vapor-deposited over a sapphire substrate. The attenuation coefficient ..cap alpha.. of the surface acoustic waves was measured from 0.8 to 30 K. The raw data are analyzed to eliminate interference effects due to splitting of the wave into two components. One of these is at the surface of the film and the other may be a ''surface skimming bulk mode'' which is at the film-substrate interface. The resultant curve of attenuation versus temperature in the superconducting region is then used to determine the distribution function of the superconducting transition temperature of the film. Although the film starts to become superconducting at 21 K and the majority of the film appears to become superconducting at 18 K, it is also found that a significant amount of the film does not become superconducting until 10 K. The difference between the attenuation measured in the normal state and the superconducting state is used to obtain the electron mean free path in the film. This is compared to values obtained from electrical measurements.

• Research Organization: Physics Department, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
• OSTI ID: 6724203
• Journal Information: J. Low Temp. Phys.; (United States), Journal Name: J. Low Temp. Phys.; (United States) Vol. 48:3; ISSN JLTPA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ATTENUATION
DISTRIBUTION FUNCTIONS
FILMS
FUNCTIONS
GERMANIUM COMPOUNDS
MEAN FREE PATH
NIOBIUM COMPOUNDS
PHYSICAL PROPERTIES
SOUND WAVES
SUPERCONDUCTING FILMS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE