Laser ablation synthesis and properties of epitaxial YBa sub 2 Cu sub 3 O sub 7-. delta. /PrBa sub 2 Cu sub 3 O sub 7-. delta. superconducting superlattices

Conference · Sun Sep 01 04:00:00 EDT 1991

OSTI ID:5278492

Lowndes, D H; Norton, D P; Zheng, X Y ^[1]; Zhu, Shen ^[2]

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1. Oak Ridge National Lab., TN (United States)
2. Tennessee Univ., Knoxville, TN (United States). Dept. of Physics and Astronomy

Pulsed laser ablation has been used to fabricate epitaxial superlattices in which c-axis-perpendicular YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) layers as thin as a single unit cell are separated by semiconducting PrBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (PBCO) layers. The superlattice {Tc} (R=0) decreases rapidly with increasing PBCO thickness, but then saturates at {Tc}{approximately}19 K, 54 K, 71 K, or 80 K, for structures containing isolated, 1-,2-,3-, or 4-cell-thick YBCO layers, respectively. Recent theoretical analyses suggest that the decrease of {Tc} and broadening of the resistive transition for the thinnest YBCO layers is most likely due either to a crossover from 3D to 2D resistive behavior, or to hole-filling in the YBCO layers caused by electron transfer from the PBCO. We find that the resistance in the superconducting transition region scales with temperature as expected for dissipation by characteristically 2D (vortex) excitations. Departures from the universal'' resistance behavior expected for a 2D Ginzburg-Landau Coulomb gas, as the YBCO thickness is increased or the PBCO thickness is decreased, can be attributed to the onset of phase coupling between the YBCO layers. Thus, the experiments show that YBCO's effective anisotropy can be greatly increased by separating very thin YBCO layers by thicker PBCO layers in superlattice structures. As a results, characteristic 2D dissipation can be observed over a greatly expanded temperature range, relative to both thicker-film and single-crystal YBCO specimens. Experiments also were carried out using two additional isostructural sets of superlattices in which the PBCO layers were replaced by more conductive Y- or Ca-doped PBCO layers, in order to alter any electron transfer from PBCO to YBCO.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5278492
• Report Number(s): CONF-9109286-1; ON: DE92000447
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABLATION
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL STRUCTURE
DIMENSIONS
ELECTROMAGNETIC RADIATION
HIGH-TC SUPERCONDUCTORS
LASER RADIATION
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PRASEODYMIUM COMPOUNDS
PRASEODYMIUM OXIDES
RADIATIONS
RARE EARTH COMPOUNDS
SUPERCONDUCTORS
SUPERLATTICES
SYNTHESIS
THERMODYNAMIC PROPERTIES
THICKNESS
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
YTTRIUM COMPOUNDS
YTTRIUM OXIDES