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 00:00:00 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), Vol. 49:18; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

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