Brillouin-Wigner theory of mixed-valence rare-earth impurities in Bardeen-Cooper-Schrieffer superconductors

Journal Article · Thu Oct 01 04:00:00 EDT 1987 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.36.5230· OSTI ID:6141497

Li, J; Gong, C; Holz, A

We present a Brillouin-Wigner-type theory for the mixed-valence rare-earth impurities in Bardeen-Cooper-Schrieffer (BCS) superconductors. The impurity is described by a degenerate Anderson model with two configurations 4f/sup 0/ and 4f/sup 1/ in the infinite-correlation limit. Two important quantities characterizing the superconducting state, i.e., the reduced transition temperature T/sub c//T/sub c0/ and the reduced specific-heat jump ..delta..C/..delta..C/sub 0/, are calculated as functions of the impurity concentration x and the valence of the 4f/sup 1/ configuration n/sub f/. The T/sub c//T/sub c0/ versus x curves obtained display exponential shapes which become steeper quickly with larger n/sub f/. The ..delta..C/..delta..C/sub 0/ versus T/sub c//T/sub c0/ curves show upward deviation with respect to the BCS law of corresponding states in contrast to the case of magnetic impurities. The theory is also fitted to the data of dilute superconducting Th/sub 1-//sub x/Ce/sub x/ alloys with a comparison to a previous Hartree-Fock theory.

• Research Organization: Center for Theoretical Physics, Nanjing University, Nanjing, People's Republic of China
• OSTI ID: 6141497
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 36:10; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ACTINIDE ALLOYS
ALLOYS
BCS THEORY
CERIUM ADDITIONS
CERIUM ALLOYS
CORRELATIONS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
IMPURITIES
PHYSICAL PROPERTIES
RARE EARTH ADDITIONS
RARE EARTH ALLOYS
SPECIFIC HEAT
SUPERCONDUCTIVITY
SUPERCONDUCTORS
THERMODYNAMIC PROPERTIES
THORIUM ALLOYS
TRANSITION TEMPERATURE
VALENCE