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

本研究采用液相外延(LPE)法制备了功能谐氧化物单晶，即反铁磁半导体La2CuO4衬底上的La2.Ksr，Cu04单晶膜，并发现了其单晶中的新功能。研究结果如下：(1)发展了一种利用红外加热炉的LPE技术--IR-LPE技术，并利用该技术在含锌La_2CuO_4衬底上成功地生长了厚度为10~250微米的La_xLt；2-x&GT；Sr_xCuO_4单晶薄膜。SrxCuO4晶体降低了器件的性能。这种方法是一种简单的方法，用环氧胶和…将厚度小于0.8 mm的氧退火晶体固定在铝板上更多的是降温。该方法使样品中的Meissner分数提高到90%左右，表明缠绕磁畴结构的钉扎中心几乎被去除。(3)用KMnO_4水溶液在化学计量比的La_2CuO_4块体单晶表面制备了氧过量La_2CuO_&lt；4+8&gt_1超导单晶层。结果表明，过量氧不仅进入大块晶体的表面部分，而且还进入大块晶体的中心部分，并且在平行于CuO_2平面的La_2CuO_4块体晶体中比垂直于CuO_2平面的La_2CuO_4块体晶体更容易渗入。(4)La_(？)lt；1-x&Gt；Sr_xCuO_4单晶薄膜的超导性能与薄膜厚度有关，当薄膜厚度小于80um时，超导性能最好。在La_xt；1-x&gt；sr_xCuO_4单晶薄膜中观察到了本征约瑟夫森效应。1×6×15μm^3。

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