Paraconductivity in nonuniform Josephson junctions

Technical Report · Thu Jul 01 04:00:00 EDT 1976

OSTI ID:7256129

Walker, P L

The Time Dependent Ginzburg-Landau equation is believed to describe the dynamics of the fluctuating order parameter of superconductors operated above their superconducting transition temperature, T/sub c/. In this theory the relaxation rate of the fluctuating order parameter is a linear function of temperature T for T greater than or equal to T/sub c/. However, recent experiments utilizing pair tunneling in Al--Al/sub 2/O/sub 3/--Pb junctions to directly measure the order parameter relaxation rate have indicated suppression of the relaxation rate from linearity over a temperature region much larger than the Ginzburg critical region. In order to explain this behavior two possible mechanisms are presented: First, the effect of random variations of the junction barrier thickness is calculated assuming Gaussian statistics and a Gaussian correlation function for the spatial variation in barrier thickness. Variations in thickness of root mean square amplitude of 1 A and wavelength of 18,000 A are needed to explain the data. Second, the effect of static fluctuations of the local T/sub c/ of the aluminum film on the dynamic order parameter is calculated in the Gaussian approximation. Fluctuations of average size approximately equal to the correlation length and mean square amplitude approximately 0.058 give good agreement with the experimental data.

• Research Organization: California Univ., Riverside (USA). Dept. of Physics
• DOE Contract Number: EY-76-S-03-0034
• OSTI ID: 7256129
• Report Number(s): TID-27577
• Country of Publication: United States
• Language: English

Related Subjects

656102* -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM
CRYSTAL STRUCTURE
ELEMENTS
FLUCTUATIONS
FUNCTIONS
GAUSS FUNCTION
GINZBURG-LANDAU THEORY
GRAIN SIZE
JOSEPHSON JUNCTIONS
METALS
MICROSTRUCTURE
ORDER PARAMETERS
PHYSICAL PROPERTIES
RELAXATION
SIZE
SUPERCONDUCTING JUNCTIONS
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE
VARIATIONS