Double Layered Thin Film Fabrication of a/c-controlled YBCO and Manganites, and Tunable Microwave Filters

双层铁磁/高温超导体（HTS）可用于移动的电话基站的可调谐微波滤波器。磁场改变了铁磁层的磁导率，从而改变了微波在高温超导层上的传播。有必要获得完成这些功能的单层和双层。此外，它是重要的阐明在磁场（H）下的高温超导体的微波吸收（MA），在双层沉积下的退化问题和薄膜在应用期间的经过退化。在本项目中，我们研究了[1] Fe-LSMO和-LBMO单层薄膜的生长，[2] LSMO/YBCO和LBMO/YBCO（YBCO：HTS-层）双层薄膜的沉积及其退化，[3]磁场下高温超导YBCO和超晶格中的微波吸收。我们成功地在超低温下培育出了它们。 关于我们 固化并获得非常光滑的膜。我们可以完全控制a/c取向生长，并阐明了a/c取向生长的机理<surface migration>。LSMO和LBMO薄膜可以在超低温下生长。LSMO呈二维阶梯状生长模式。LSMO覆盖层可以生长在a-YBCO衬底上，但a-YBCO的一部分被转化为c-YBCO。在LBMO衬底上可以生长出高质量的YBCO覆盖层。在双层沉积过程中，下层LBMO的结晶度没有下降，但双层表面变得粗糙。当LBMO沉积在YBCO层上时，表面非常光滑，但在双层沉积过程中，YBCO层下的LBMO被降解。在几年的时间内，a-YBCO/Mg 0的结晶度表现出较大的衰减，但a-YBCO/LAO的结晶度没有衰减。采用PLD技术制备了高Tc（86 K）的a-YBCO和c-YBCO，并在H. MA是更大的c-YBCO比a-YBCO。H//a的MA比H//c的MA小，这表明a-YBCO更适用于双层可调谐微波滤波器。通过理论分析阐明了<excess screening current mechanism>一个主要因素是MA。我们测量了LCMO/YBCO超晶格的MA，发现了一个很重要的事实，即垂直于平面的H的MA很大，而平行于平面的H的MA可以忽略不计。因此，我们可以建议，我们可以最大限度地减少微波吸收的HTS层的平行磁场时，铁/HTS双层（超晶格）将用于可调谐微波滤波器在不久的将来。少

Double layers of Ferromagnetic/Hi-Tc-Superconductors (HTS) can be used for tunable microwave filters at base stations of mobile phone system. Permeability of Ferro-layer is modified by magnetic field, leading to modification of microwave propagation on HTS-layer. It is necessary to obtain single-layers and double-layers which complete such functions. Further, it is important to elucidate microwave absorption (MA) in HTS under magnetic field (H), problems of deteriorations under the double layers depositions and elapsed-degradations of thin films in application periods. In this project, we studied [1] thin film growths of Ferro-LSMO and-LBMO single layers, [2] double layer depositions of LSMO/YBCO and LBMO/YBCO (YBCO: HTS-layer), and their degradations, [3] microwave absorptions in HTS-YBCO and Superlattices under magnetic field.YBCO thin films were deposited on Mg0 and LAO substrates by Ion Beam Sputtering (IBS) with oxygen plasma supply. We succeeded to grow them at ultra-low temperat … More ures and obtained extremely smooth films. We could control a/c-orientation growths completely and elucidated a mechanism of a/c-orientations <surface migration>. Fine crystalline LSMO and LBMO thin films could be grown at ultra-low temperatures. LSMO showed 2D step-terrace growth mode. LSMO over-layers could be grown on a-YBCO under-layers but a part of a-YBCO was changed into c-YBCO. High quality YBCO over-layers could be grown on LBMO under-layers. During the double-layer depositions, the crystallinity of under-LBMO was not degraded but the double-layer surface was much roughened. The surface was very smooth when LBMO was deposited on YBCO layers but under-YBCO was degraded during the double-layer depositions. The crystallinity showed large elapsed-degradations for a few years for a-YBCO/Mg0 but not for a-YBCO/LAO. It was known that the degradation is concerned with lattice matching.High Tc (86 K) a-YBCO and c-YBCO were fabricated by PLD, and their MA was investigated under H. MA was larger for c-YBCO than for a-YBCO. MA was smaller for H//a than for H//c then it was clarified that a-YBCO is more useful for the double-layered tunable microwave filters. It was elucidated by theoretical analysis that an <excess screening current mechanism> is a major factor for MA. We measured MA on LCMO/YBCO superlattice, and found a quite important fact that MA is large for H perpendicular to the plane but negligible small for H parallel to the plane. Thus we could propose that we can minimize the microwave absorption in HTS-layers for the parallel magnetic field when the Ferro/HTS double-layers (superlattices) will be used for tunable microwave filters in the near future. Less