Charge-imbalance relaxation in the presence of a pair-breaking interaction in superconducting AlEr films
The charge-imbalance relaxation rate, 1/F*tau/sub Q/*, has been measured in dirty superconducting AlEr films in which Er is a pair-breaking magnetic impurity that induces charge relaxation through elastic exchange scattering. Measurements were made in the range 0.1< or approx. =..delta..(T)/k/sub B/T/sub c/< or approx. =1.4 for Er concentrations varying from 21 to 1660 at. ppm that produced estimated exchange scattering rates, tau/sup -1//sub S/, from about 10/sup 9/ sec/sup -1/ to 5 x 10/sup 10/ sec/sup -1/. Measured values of 1/F*tau/sub Q/* were in good agreement with the Schmid-Schoen expression, 1/F*tau/sub Q/*=(pi..delta../4k/sub B/T/sub c/tau/sub E/) (1+2tau/sub E//tau/sub S/)/sup 1/2/, for ..delta../k/sub B/T/sub c/< or approx. =0.8, where tau/sup -1//sub E/ is the electron-phonon scattering rate estimated from the measured transition temperature. For larger values of ..delta../k/sub B/T/sub c/, the relaxation rate increased less rapidly with ..delta... The appropriate Boltzmann equation was solved on a computer to obtain values for 1/F*tau/sub Q/* in the range 0.5< or =T/T/sub c/< or =0.999 999. The computed values of 1/F*tau/sub Q/* agreed with several analytic expressions valid for ..delta../k/sub B/T/sub c/<<1, but not with the experimental data: The computed curves increased more rapidly than linearly with ..delta../k/sub B/T/sub c/ near T/sub c/, and the shape of the 1/F*tau/sub Q/* vs ..delta../k/sub B/T/sub c/ curves was qualitatively different. This discrepancy suggests that either the generally accepted expression for exchange charge relaxation is incorrect, or that the Boltzmann equation is inappropriate for these calculations.
- Research Organization:
- Univ. of California, Berkeley, CA (United States). Dept. of Physics
- OSTI ID:
- 7052555
- Journal Information:
- Phys. Rev. B: Condens. Matter; (United States), Vol. 23:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM BASE ALLOYS
SUPERCONDUCTIVITY
ERBIUM ALLOYS
BOLTZMANN EQUATION
EXCHANGE INTERACTIONS
RELAXATION
SUPERCONDUCTING FILMS
ALLOYS
ALUMINIUM ALLOYS
DIFFERENTIAL EQUATIONS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
EQUATIONS
FILMS
INTERACTIONS
PHYSICAL PROPERTIES
RARE EARTH ALLOYS
360104* - Metals & Alloys- Physical Properties
656102 - Solid State Physics- Superconductivity- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena- (-1987)