Long-range ferroelectric interactions in KTaO{sub 3}/KNbO{sub 3} superlattice structures

Journal Article · Fri May 01 04:00:00 EDT 1998 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.121411· OSTI ID:627886

Christen, H; Specht, E D; Norton, D P; Chisholm, M F; Boatner, L A ^[1]

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1. Oak Ridge National Laboratory, Oak Ridge, Tennessee37831 (United States)

Symmetric superlattice structures consisting of alternating atomic-scale layers of KTaO{sub 3} and KNbO{sub 3} with variable periodicity were grown on KTaO{sub 3} substrates by pulsed laser deposition. The in-plane structure of KNbO{sub 3} closely matches that of the KTaO{sub 3} substrate, resulting in KTaO{sub 3}/KNbO{sub 3} heterostructures that are uniformly strained in-plane without misfit dislocations. This strain imposes an in-plane KNbO{sub 3} lattice spacing identical to that of the KTaO{sub 3} substrate for the temperature range 30{degree}C{lt}T{lt}700{degree}C, and a tetragonal-to-tetragonal transition is observed whose phase transition temperature T{sub c} depends on the KNbO{sub 3} layer thickness. The in-plane strain results in a significant increase in this ferroelectric-paraelectric T{sub c} for superlattices with relatively thick KNbO{sub 3} layers (T{sub c}=535{degree}C for a 17 nm thick layer, as compared to 435{degree}C for bulk KNbO{sub 3}) and for K(Nb{sub 0.5}Ta{sub 0.5})O{sub 3} random-alloy thin films. As the superlattice period decreases, a reduction of T{sub c} is observed. For superlattices with periodicities of 50 {Angstrom} or less, the Curie temperature is identical to that of the K(Ta{sub 0.5}Nb{sub 0.5})O{sub 3} random-alloy film, indicating significant long-range ferroelectric coupling across the KTaO{sub 3} layers. {copyright} {ital 1998 American Institute of Physics.}

• OSTI ID: 627886
• Journal Information: Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 20 Vol. 72; ISSN 0003-6951; ISSN APPLAB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
66 PHYSICS
FERROELECTRIC MATERIALS
NIOBATES
PEROVSKITES
PHASE TRANSFORMATIONS
POTASSIUM COMPOUNDS
STRAINS
SUPERLATTICES
TANTALATES