Inequalities for. delta. (T)/k/sub B/T/sub c/: A test for weak-coupling theory applied to high-T/sub c/ superconductors

Journal Article · Mon Feb 01 04:00:00 EST 1988 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.37.2235· OSTI ID:5640033

Combescot, R

High-T/sub c/ superconductors should be strong or weak-coupling superconductors depending on the mechanism responsible for superconductivity. The answer will allow one to discriminate between various theories. In order to have a definite criterion independent of band-structure effects, we investigate the effect of a rapidly varying density of states in weak-coupling Bardeen-Cooper-Schrieffer (BCS) theory. We show that, whatever the density of states, ..delta..(0)/k/sub B/T/sub c/less than or equal to2. At finite temperature, this is generalized into ..delta..(T)less than or equal to1.13..delta../sub BCS/(T) where ..delta../sub BCS/ is the standard result for a constant density of states. If the gap is anisotropic, the same inequalities must be satisfied by the minimum of the gap over the Fermi surface. These exact results allow one to test whether high-T/sub c/ superconductors are weak or strong coupling.

• Research Organization: Groupe de Physique des Solides de l'Ecole Normale Superieure, 24 rue Lhomond, 75231 Paris Cedex 05, France
• OSTI ID: 5640033
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 37:4; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

656100* -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BCS THEORY
ENERGY GAP
ENERGY-LEVEL DENSITY
PHYSICAL PROPERTIES
SUPERCONDUCTORS
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE