Preparation of Single-Crystalline Films of Functional Harmonic Oxides by Liquid Phase Epitaxy

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n this study, single crystals of functional harmonic oxides, which are single-crystalline films of antimagnetic superconductor La2.KSr,Cu04 on the substrate of antiferroamgnetic semiconductor La_2CuO_4, were prepared by liquid phase epitaxial (LPE) method, and then new functions in their single crystals were discovered. The research results were summarized as follows :(1) A new LPE technique using an infrared heating furnace, IR-LPE, was developed, and by this technique a-axis orientated singleTcrystalline films of La_<2-x>Sr_xCuO_4 with the thickness of 10 〜 250 um were grown successfully on the substrate of Zn-substituted La_2CuO_4.(2) A new detwinning technique of La_<2-x>Sr_xCuO_4 crystals, which was named thermal difference method, was developed, since the twined domain structure in La_<3-x>Sr_xCuO_4 crystals lowers the device properties. This method is a simple, where the oxygen-annealed crystals of thickness less than 0.8 mm were fixed on the aluminum plate using epoxy glue and … More then cooled down. The Meissner fraction in the sample increased up to about 90 % by this method, and this result suggests that the pinning centers of the twined domain structure were almost removed.(3) Superconducting single-crystalline layer of oxygen-excess La_2CuO_<4+8> was prepared in (Be surface of bulk single crystal of stoichiometric La_2CuO_4 by oxidization using KMnO_4 aqueous solution. It was found that the excess oxygen introduced to not only the surface part but also the center part of the bulk crystals, and that the excess oxygen penetrates into the La_2CuO_4 bulk crystal parallel to the CuO_2 planes easier than perpendicular to the CuO_2 planes.(4) The superconducting properties of the single-crystalline films of La_<1-x>Sr_xCuO_4 depended on the film thickness, and were superior for the film thickness less than 80 urn. The intrinsic Josephson effects were observed successfully in the single-crystalline films of La_<1-x>Sr_xCuO_4 by processing toabridge-shapeof1 x 6 x 15 μm^3. Less