Synthesis and properties of La[sub 2[minus]x]Sr[sub x]CuO[sub 4] thin films

Miscellaneous · Wed Jan 01 00:00:00 EST 1992

OSTI ID:7114766

Kao, H L

This thesis describes fabrications and charge transport properties of single crystal La[sub 2[minus]x]Sr[sub x]CuO[sub 4] thin films. The ability to control both the film growth and orientation have made it possible to systematically investigate the transport properties along CuO[sub 2] planes and across planes in thin films. Excellent quality La[sub 2[minus]x]Sr[sub x]CuO[sub 4] epitaxial thin films of widely varying Sr contents have been grown on SrTiO[sub 3] substrates by in-situ off-axis magnetron sputtering. In addition to c-axis oriented films, the (103) and (109) films, which have CuO[sub 2] planes uniaxially tilted off the substrate surface, were also successfully produced by using vicinal substrates. The growth mechanism responsible for this symmetry breaking is understood based on a surface step model. The authors studied the in-plane resistivity of these La[sub 2[minus]x]Sr[sub x]CuO[sub 4] thin films up to 800K and found a systematic evolution of the charge transport mechanism in the CuO[sub 2] layers as a function of doping. The T-linear resistivity is observed in the region of optimal superconducting properties. Below x[approximately]0.15, the authors observed evidence for resistivity saturation. In the heavily doped region, a power law dependence dominates the resistivity over the entire temperature range. The resistivity across the CuO[sub 2] planes (p[sub c]) as function of doping were derived by measuring the (103) and (109) films. p[sub c] and p[sub c]/p[sub ab] decrease with increase of Sr as well as temperature. The two dimensional transport in x [le] 0.15 is recognized from the large anisotropy and temperature dependence. However, the temperature dependence of p[sub c]/p[sub ab] is substantially suppressed where Sr exceeds 0.25, and the magnitude is close to the predictions of band calculation. The crossover from two-dimensional to anisotropic three-dimensional transport occurs near the disappearance of bulk superconductivity.

• Research Organization: Columbia Univ., New York, NY (United States)
• OSTI ID: 7114766
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
SUPERCONDUCTING FILMS
ELECTRIC CONDUCTIVITY
FABRICATION
CUPRATES
HIGH-TC SUPERCONDUCTORS
INTERMETALLIC COMPOUNDS
LANTHANUM OXIDES
STRONTIUM OXIDES
TEMPERATURE DEPENDENCE
ALKALINE EARTH METAL COMPOUNDS
ALLOYS
CHALCOGENIDES
COPPER COMPOUNDS
ELECTRICAL PROPERTIES
FILMS
LANTHANUM COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
STRONTIUM COMPOUNDS
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
360207* - Ceramics
Cermets
& Refractories- Superconducting Properties- (1992-)
360201 - Ceramics
Cermets
& Refractories- Preparation & Fabrication