Thermal and electronic properties of rare-earth Ba/sub 2/Cu/sub 3/O/sub x/ superconductors

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

DOI:https://doi.org/10.1103/PhysRevB.37.1604· OSTI ID:5530825

Heremans, J; Morelli, D T; Smith, G W; Strite, III, S C

We have measured the electrical resistivity, thermal conductivity, and specific heat of a series of high-temperature superconducting compounds of the form RBa/sub 2/Cu/sub 3/O/sub 7/, with R = Y, Eu, Gd, Dy, and Er. Our results show that the afore-mentioned physical properties are virtually identical for all samples considered. In particular, the molar specific heats are identical to within +- 2% and exhibit Debye-type behavior. We observe a nearly constant thermal conductivity above T/sub c/, but a rather sudden increase developes as the temperature is lowered below the critical temperature. The electrical resistivity is nearly linear in the normal state. Thermal and electrical conductivities indicate that for T>T/sub c/, the predominant electron scattering mechanism is due to phonon interactions. Using electrical resistivity data and the Wiedemann-Franz law, we estimate the magnitude of the electronic component of the thermal conductivity to be an order of magnitude smaller than the measured thermal conductivity. We thus conclude that heat transport is predominantly by phonons. The enhancement of the lattice conduction below the critical temperature is understood as a reduction of carrier-phonon scattering as electrons condense into Cooper pairs. This lends support to standard Bardeen-Cooper-Schrieffer-type superconductivity. An estimate of the superconducting transition temperatures is made using the electron-phonon coupling constants and Debye temperatures deduced from the data which brackets the observed T/sub c/ quite well. We discuss the thermal conductivity at very low temperature in terms of a phonon mean-free path limited by pores in the samples.

• Research Organization: Physics Department, General Motors Research Laboratories, Warren, Michigan 48090-9055
• OSTI ID: 5530825
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Vol. 37:4
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BARIUM OXIDES
ELECTRIC CONDUCTIVITY
ELECTRON-PHONON COUPLING
SPECIFIC HEAT
THERMAL CONDUCTIVITY
TRANSITION TEMPERATURE
COPPER OXIDES
DYSPROSIUM OXIDES
ERBIUM OXIDES
EUROPIUM OXIDES
GADOLINIUM OXIDES
YTTRIUM OXIDES
BCS THEORY
DEBYE TEMPERATURE
EXPERIMENTAL DATA
SUPERCONDUCTORS
TEMPERATURE DEPENDENCE
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
DATA
DYSPROSIUM COMPOUNDS
ELECTRICAL PROPERTIES
ERBIUM COMPOUNDS
EUROPIUM COMPOUNDS
GADOLINIUM COMPOUNDS
INFORMATION
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360204* - Ceramics
Cermets
& Refractories- Physical Properties
656100 - Condensed Matter Physics- Superconductivity