Isotope-shift exponent, pressure coefficient of [ital T][sub [ital c]], and the superconducting-gap ratio within the van Hove scenario

Journal Article · Sun May 01 04:00:00 EDT 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.49.13070· OSTI ID:6950581

Sarkar, S; Das, A N ^[1]

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1. Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Calcutta 700 064 (India)

Exact expression for the isotope-shift exponent and the pressure coefficient of the transition temperature are derived from the BCS gap equation for a density of states (DOS) with a van Hove singularity (VHS). The variations of these quantities with the shift of the Fermi level from the VHS and with [ital T][sub [ital c]] are discussed. The superconducting gap-to-[ital T][sub [ital c]] ratio (2[Delta][sub 0]/[ital T][sub [ital c]]) is also studied. The value of 2[Delta][sub 0]/[ital T][sub [ital c]] lies in the range from 3.53 to 4 for the DOS with a VHS at the Fermi level. A comparison of theoretical predictions with experimental results of high-[ital T][sub [ital c]] oxide systems are made. A qualitative good agreement is obtained for the pressure coefficient of [ital T][sub [ital c]].

• OSTI ID: 6950581
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 49:18; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360207* -- Ceramics
Cermets
& Refractories-- Superconducting Properties-- (1992-)
665411 -- Basic Superconductivity Studies-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BCS THEORY
COPPER COMPOUNDS
CUPRATES
DATA
ENERGY GAP
ENERGY LEVELS
ENERGY-LEVEL DENSITY
EXPERIMENTAL DATA
FERMI LEVEL
INFORMATION
ISOTOPE EFFECTS
NUMERICAL DATA
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PRESSURE DEPENDENCE
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
VAN HOVE THEORY