Synthesis and properties of YBa sub 2 Cu sub 3 O sub 7 and Y sub 2 Ba sub 4 Cu sub 8 O sub 16 thin films

Miscellaneous · Sun Jan 01 00:00:00 EST 1989

OSTI ID:5157674

Char, Kookrin

This work presents some transport and structural properties of YBa{sub 2} Cu{sub 3}O{sub 7} and Y{sub 2}Ba{sub 4}Cu{sub 8}O{sub 16} thin films fabricated in a desired orientation by reactive magnetron sputtering and e-beam evaporation. A reactive magnetron sputtering technique was developed for these oxide thin films. Three metal targets were co-sputtered onto SrTiO{sub 3} (100) substrates with oxygen sprayed from nearby. With postdeposition annealing, films of excellent quality with thicknesses ranging from 500 {angstrom} to 5 {mu}m were successfully made. It was found that the orientation of the films can be controlled by having the proper composition, thickness and post-deposition heat treatment. Normal state properties of YBa{sub 2}Cu{sub 3}O{sub 7} measured by resistivity and Hall coefficient show anisotropic behavior different from those of, conventional metals; it has a high resistivity {rho}{sub ab}(100K) {approximately}100 {mu}{Omega}cm linear with temperature and a low carrier density n{sub ab}(100K) {approximately}3 {times} 10{sup 21} cm{sup {minus}1} of holes. Fluctuation conductivity measurements above {Tc} shows Lawrence-Doniach type 2D to 3D crossover behavior with {xi}(0) {approximately}2{angstrom}. Upper critical field, H{sub c2}, measurements show very short coherence lengths of {xi}{sub ab}(0) {approximately}16 {angstrom} and {xi}{sub c}(0) {approximately}2 {angstrom}. These short coherence lengths together with the high transition temperature cause unusually large flux motion. High critical current densities, J{sub c}, in excess of 1 x 10{sup 7} A/cm{sup 2} at 4.2 K and 1 {times} 10{sup 6} A/cm{sup 2} at 77 K were measured in the c-axis oriented films. An ordered defect structure Y{sub 2}Ba{sub 4}Cu{sub 8}O{sub 16} has discovered and its properties were studied. It has a {Tc} of 81 K and is characterized by its lower normal state resistivity and lower Hall coefficient compared to YBa{sub 2}Cu{sub 3}O{sub 7}.

• Research Organization: Stanford Univ., CA (United States)
• OSTI ID: 5157674
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BARIUM OXIDES
CRYSTAL STRUCTURE
FABRICATION
PHYSICAL PROPERTIES
COPPER OXIDES
YTTRIUM OXIDES
ANISOTROPY
CRITICAL CURRENT
CRITICAL FIELD
CURRENT DENSITY
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
HALL EFFECT
LOW TEMPERATURE
SPUTTERING
THIN FILMS
TRANSITION TEMPERATURE
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
CURRENTS
ELECTRIC CURRENTS
FILMS
MAGNETIC FIELDS
OXIDES
OXYGEN COMPOUNDS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
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