Effects of spin-flip scattering on the dynamics of the superconducting order parameter

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1980

OSTI ID:5473620

Aspen, F E

Measurements of the imaginary part of the pair-field susceptibility X'' have been carried out on dirty-limit Al-Er alloy films. Aluminum films with erbium concentrations of up to one atomic percent were incorporated as the low T/sub c/ film of an asymmetric Josephson junction. The excess current I/sub ex/ due to pair tunneling was measured as a function of the bias voltage V and of the magnetic field H, applied in the plane of the junction, at temperatures within 20% of the critical temperature T/sub c/. Comparison to theory was facilitated by noting that X'' (..omega..,k) is proportional to I/sub ex/(V,H) where the frequency ..omega.. and wave-number k are related to V and H via the Josephson relations. These experiments represent the first measurements of X''(..omega..,k) as a function of the pair-breaking parameter p. Spin-flip scattering from the Er impurities resulted in values of p up to 0.1. Several important results were obtained from these experiments. At temperatures above T/sub c/ it was verified that the diffusive time-dependent Ginzburg-Landau equation for order-parameter fluctuations is valid in the presence of pair-breaking. The diffusion rate was found to be reduced by the pair-breaking to a value which is in quantitative agreement with theory. The characteristic frequencies of X'' were determined from the measurements of I/sub ex/ below T/sub c/ by fitting to a functional form which exhibits the essential features of the various theories. Measurements of X''(..omega..,k) as a function of pair momentum q were carried out by applying a dc transport current along the Al-Er film while recording the I-V charateristics of the junction. Finally, measurements of X''(..omega..,k) for Ag/Pb proximity sandwich superconductors were carried out.

• Research Organization: Minnesota Univ., Minneapolis (USA)
• OSTI ID: 5473620
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
420201 -- Engineering-- Cryogenic Equipment & Devices
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOYS
ALUMINIUM ALLOYS
ERBIUM ADDITIONS
ERBIUM ALLOYS
FILMS
GINZBURG-LANDAU THEORY
INELASTIC SCATTERING
JOSEPHSON JUNCTIONS
JUNCTIONS
RARE EARTH ADDITIONS
RARE EARTH ALLOYS
SCATTERING
SPIN FLIP
SUPERCONDUCTING FILMS
SUPERCONDUCTING JUNCTIONS