Specific Heat of YBa₂Cu₃O₇: Volume Fraction of Superconductivity; Parameters Characteristic of the “Ideal” Superconducting State

Conference · Thu Jan 03 04:00:00 EST 1991

OSTI ID:5591648

Phillips, Norman E. ^[1]; Fisher, R. A. ^[1]

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1. Lawrence Berkeley Laboratory (LBL), Berkeley, CA (United States)

Experimentally determined parameters for YBa₂Cu₃O₇ (YBCO) are strongly sample dependent. However correlations among parameters derived from the specific heat (C) suggest that the variation reflects a variation in the volume fraction of superconductivity, (f_s). From these correlations f_s can be quantitatively determined and values of parameters characteristic of fully superconducting material can be derived. With additional assumptions, it is also possible to estimate the Sommerfeld constant (γ) for the fully normal state. Among the parameters of particular importance in establishing the correlations are the discontinuity in C [ΔC(T_c)] at the critical temperature (T_c) and concentration (n₂) of localized Cu²⁺ magnetic moments. These are located on the YBCO lattice, at least in substantial measure, and are directly correlated with f_s. From an analysis of C in the vicinity of T_c it is possible to obtain information on the strength of the coupling responsible for the superconductivity; from a comparison of γ with that calculated for the bare density of states (γ_bs) the electron phonon enhancement parameter (λ) can be obtained.

• Research Organization: Lawrence Berkeley Laboratory (LBL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5591648
• Report Number(s): LBL--30435; CONF-910190--3; ON: DE91011827
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
HIGH-TC SUPERCONDUCTORS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SPECIFIC HEAT
SUPERCONDUCTIVITY
SUPERCONDUCTORS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
YTTRIUM COMPOUNDS
YTTRIUM OXIDES