Researches on Transport Property and Electronic Structure of Metallic Superlattices, Metal Oxides and Metal Halogenides

(1)作为材料科学系联合使用的主要研究设备之一，于1988年安装了一台MBE(分子束外延)成膜机。GRANT部分用于激活这项分子束外延工作，即研究金属超晶格。选择Eu和锶作为超晶格元素是因为Eu具有自旋矩，而锶在原子大小上与Eu非常相似，而二价态没有自旋，因此可以预期与超晶格周期有关的有趣的磁性行为。以BaF_2(111)面为衬底，外延生长锶，Eu紧随其后。用RHEED和X-射线衍射仪证明了外延的存在。在1K以下，初步观察到铁磁磁化强度。(2)目前最重要的金属氧化物应该是CuO_2基高T_c超导体。发现了一种简单有效的控制Y_1Ba2Cu3O_y中氧浓度的方法，其中包括在常压…中加热对超导体在微波频段的导电特性进行了研究。与直流测量不同，IRI微波测量的电阻频率范围几乎不受晶界的影响。(3)以溴和ICI插层石墨化合物作为金属卤化物，通过悬挂在卤素和CCl_4溶液表面上方，在室温下将Br2或ICl插入Nihon Carbon公司的KIKAFILM(相当于联合碳化物公司的铝箔)中。在反应过程中，原位测量了电阻、磁阻和霍尔效应。通过分析得到的数据，推导出了导电洞和电子浓度与反应时间的关系。用氯气和镍芯片共封的方法将GaCl3嵌入玻璃安瓶中。第一步化合物和第二步化合物是在室温下得到的。用含有低级化合物的安瓶，在几十ﾟ℃下加热，制得高级化合物。为了与首席研究者提出的理论进行比较，需要研究GaCl3-GICs电导率的阶段依赖关系。较少

(1)As one of the main research equipments for joint use in the Department of Materials Science, a MBE(molecular beam epitaxy)film growing machine was installed in 1988. The Grant was partially used for activating this MBE work, i. e., a study of metallic superlattice. Europium and strontium were chosen as the superlattice elements, because that Eu has a spin moment and Sr which is very similar to Eu in atomic size and divalency has no spin, so that interesting magnetic behaviors dependent on superlattice periods are expected. By using BaF_2 (111)face as the substrate, Sr was grown epitaxially and Eu followed. The epitaxy was proved by RHEED and X-ray diffraction. Below about 1 OK, a ferromagnetic magnetization was observed as a preliminary measurement.(2) The most important metal oxides at present should be CUO_2-based high Tc superconductors. An effective simple controlling treatment for the oxygen concentration was found in Y_1Ba_2CU_3O_y, which included a heating in the normal-atmos … More phere and a successive quenching.Researches on the conduction property of yttrium- and bismuth- oxides superconductors in the microwave frequency range were done. Different from the DC measurement, the resistance measurement iri microwave frequency range is hardly influenced by grain boundaries. It was found that the measured surface resistance showed an anomaly which related to an uncommomly large effective surface area.(3)The bromine and ICI intercalated graphite compounds were taken up as the metal halogenides, Br_2 or ICl were intercalated into KIKAFILM of Nihon Carbon Co. (an equivalent material to grafoil of the Union Carbide Co.)in the room temperature by hanging above the surface of solution of halogen and CCl_4. During the reaction term, resistance, magnetoresistance and Hall effect were in-situ measured. By analysing the obtained data, the reaction-time dependence of the concentrations of conduction holes and electrons was deduced.GaCl_3 was intercalated by co-sealing with chlorine gas and a NIKAFILM chip into a glass ampule. The first and second stage compounds were obtained at the room temperature. Higher stage compound were made by puming the ampule which included a low stage compound and heating it at the temperature of several tens ﾟC. The stage dependence of the conductivity of GaCl_3-GICs is to be investigated in order to compare to the proposed theory of the head investigator. Less