CHARGE-IMBALANCE RELAXATION IN THE PRESENCE OF A PAIR-BREAKING INTERACTION IN SUPERCONDUCTING AlEr FILMS
The charge-imbalance relaxation rate, 1/F*{sub T{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 {approx}< {Delta}(T)/k{sub B}T{sub c} {approx}< 1.4 for Er concentrations varying from 21 to 1660 at. ppm that produced estimated exchange scattering rates, {tau}{sub S}{sup -1}, from about 10{sup 9} sec{sup -1} to 5 x 10{sup 10} sec{sup -1}. Measured values of 1/F*{sub T{sub Q*}} were in good agreement with the Schmid-Schoen expression, 1/F*{sub T{sub Q*}}=({pi}{Delta}/4k{sub B}T{sub c}{tau}{sub E}) x (1+2{tau}{sub E}/{tau}{sub S}){sup 1/2}, for {Delta}/k{sub B}T{sub c} {approx}< 0.8, where {tau}{sub E}{sup -1} 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*{sub T{sub Q*}} in the range 0.5 {approx}< T/T{sub c} {approx}< 0.999999. The computed values of 1/F*{sub T{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*{sub T{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:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- Materials Sciences Division
- DOE Contract Number:
- DE-AC02-05CH11231
- OSTI ID:
- 1000032
- Report Number(s):
- LBL-11201; TRN: US201024%%267
- Journal Information:
- Physical Review B, Vol. 23, Issue 3; ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
Similar Records
Charge-imbalance relaxation in the presence of a pair-breaking supercurrent in dirty, superconducting Al films
Addendum to ''Quasiparticle branch mixing rates in superconducting aluminum''