Growth mechanisms and superconductivity of ultrathin Y[sub 1]Ba[sub 2]Cu[sub 3]O [sub 7[minus][ital x]] epitaxial films on (001) MgO substrates

Journal Article · Mon Jun 21 04:00:00 EDT 1993 · Applied Physics Letters; (United States)

DOI:https://doi.org/10.1063/1.109072· OSTI ID:6612286

Zhu, S ^[1]; Lowndes, D H; Chakoumakos, B C; Pennycook, S J ^[2]; Zheng, X; Warmack, R J ^[3]

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1. Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996 (United States)
2. Solid State Division, Oak Ridge National Laboratory, P. O. Box 2008, Oak Ridge, Tennessee 37831-6056 (United States)
3. Health and Safety Research Division, Oak Ridge National Laboratory, P. O. Box 2008, Oak Ridge, Tennessee 37831-6123 (United States)

Ultrathin YBa[sub 2]Cu[sub 3]O [sub 7[minus][ital x]] films grown on (001) MgO substrates by pulsed-laser ablation exhibit a transition from terraced-island growth to spiral growth at [similar to]4--5 unit cell thickness in films grown at 720 [degree]C. The transition appears at greater thickness in films grown at higher growth temperatures. Observations of the morphology of ultrathin films indicate that the film--substrate interfacial interaction plays an important role when films are only several unit-cells thick. Plastic deformation and oxygen disorder both may affect the epitaxial quality and superconducting properties. However, superconducting properties can be improved by achieving a relatively strain-free state. Our observations of the growth transition and resistivity measurements show that this state occurs in the thicker grains of nominally 3.5 nm films grown at 800 [degree]C and in nominally 7 nm films grown at both 720 and 800 [degree]C. These results also imply that a strain-relieving buffer layer will improve the superconductive properties of ultrathin YBa[sub 2]Cu[sub 3]O[sub 7[minus][ital x]] films grown on misfit substrates.

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6612286
• Journal Information: Applied Physics Letters; (United States), Journal Name: Applied Physics Letters; (United States) Vol. 62:25; ISSN APPLAB; ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360207 -- Ceramics
Cermets
& Refractories-- Superconducting Properties-- (1992-)
ABLATION
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL GROWTH
DIMENSIONS
ELECTROMAGNETIC RADIATION
ELECTRON MICROSCOPY
EPITAXY
FILMS
HIGH-TC SUPERCONDUCTORS
LASER RADIATION
MICROSCOPY
MORPHOLOGY
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RADIATIONS
RESIDUAL STRESSES
SCANNING ELECTRON MICROSCOPY
STRESSES
SUPERCONDUCTING FILMS
SUPERCONDUCTORS
TEMPERATURE EFFECTS
THERMODYNAMIC PROPERTIES
THICKNESS
THIN FILMS
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
YTTRIUM COMPOUNDS
YTTRIUM OXIDES