Transport studies on single-crystal YBa sub 2 Cu sub 3 O sub 7-x

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:5944179

Hagen, S J

This thesis describes anisotropic transport studies on the 90 K superconductor YBa{sub 2}Cu{sub 3}O{sub 7-x}. Resistivity anisotropy, fluctuation conductivity (paraconductivity), and thermal conductivity anisotropy measurements in high-quality single crystals demonstrate highly two-dimensional electronic properties in this material. Parallel to the CuO{sub 2} planes the resistivity {rho}{sub ab} (300 K) {approximately} 150-200 {mu}{Omega}-cm is clean and metallic, with k{sub F}l {approximately} 30 and l {approximately} 70 {angstrom} at 100 K. Normal to the planes, however, the resistivity is {approximately}10{sup 2} larger, possibly with an anomalous temperature dependence, indicating nonmetallic conduction in this direction. Thermal conductivity measurements also find substantial differences between in-plane and out-of-plane conduction. In-plane paraconductivity measurements show that superconducting fluctuations in the normal state of YBa{sub 2}Cu{sub 3}O{sub 7-x} exhibit two-dimensional Aslamazov-Larkin behavior, with no indication of a crossover to three-dimensional behavior near the superconducting transition. There is also evidence that the critical fluctuation region in YBa{sub 2}Cu{sub 3}O{sub 7-x} is much wider ({epsilon}{sub c} {approximately} 10{sup {minus}2}) than in conventional superconductors. Two additional experiments are described in the appendices. Thermopower measurements in ceramic YBa{sub 2}Cu{sub 3-x}Ni{sub x}O{sub 7-x} test the effect of Cu substitution on superconductivity and carrier concentration, and resistivity measurements on single-crystals of the 10 K superconductor Bi{sub 2}Sr{sub 2}CuO{sub 6} find evidence for large anisotropies in this newer family of copper-oxide superconductors.

• Research Organization: Princeton Univ., NJ (USA)
• OSTI ID: 5944179
• 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
CRYSTALS
DATA
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRONIC STRUCTURE
EXPERIMENTAL DATA
HIGH-TC SUPERCONDUCTORS
INFORMATION
LOW TEMPERATURE
MONOCRYSTALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SUPERCONDUCTORS
THERMAL CONDUCTIVITY
THERMODYNAMIC PROPERTIES
THERMOELECTRIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES