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Structure and Property of Single Crystalline MgO Films Embedded Fine Metal Crystallites

嵌入细金属微晶的单晶氧化镁薄膜的结构与性能

基本信息

批准号：
61420018
负责人：
MIHAMA Kazuhiro
金额：
$ 24万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1988
项目状态：
已结题

项目摘要

During the term of the research, composite films of metal-magnesium oxide are studied, Au, Pu, Pb, Fe, Cr and Ti being chosen as metal and also Ge and PbS as semiconductor. In most metals, metal is embedded homogeneously inside single crystalline magnesium oxide in the form of fine metal crystallites of a few nm in size with theepitaxial orientation. For Ti, fine TiO crystallites of less than 1 nm in size are grown epitaxially inside magnesium oxide film. For Ge, amorphous Ge fine particles are grown. These specimens are characterized by high resolution electron microscopy and the following resuts are obtained : (1) the thickness of metal crystallites are estimated to be a few atomic layers ,(2) the strain analysis of the periphery of Fe particles arised from the accomodation with the magnesium oxide lattice is carried out and (3) the observation of atomic clusters as well as isolated single atoms are carried out by using the off-Bragg condition.Recently, the electric resistance and the magnetization of these composite films are measured to clarify the physical properties. The negative temperature coefficients of the resistivity in the temperature region of -150゜C to 250゜C for MgO-Au and MgO-Pd composite films and the behavior can be explained in terms of "activation-tunnelling model" The magnetization for extremely low temperature is measured with SQUID for MgO-Fe composite films and the formation of the spin glass is confirmed.

在研究期间，以Au、Pu、Pb、Fe、Cr、Ti为金属，以Ge、PbS为半导体，研究了金属-氧化镁复合薄膜。在大多数金属中，金属均匀地嵌入在单晶氧化镁中，形成几纳米大小的微细金属晶体，具有外延取向。对于Ti，在氧化镁薄膜内外延生长出尺寸小于1nm的细小TiO晶。对于锗，生长出无定形的锗细颗粒。利用高分辨率电子显微镜对这些样品进行了表征，得到以下结果：(1)估计金属晶体的厚度为几个原子层；(2)对与氧化镁晶格配合产生的铁颗粒外围进行了应变分析；(3)利用off-Bragg条件对原子团簇和孤立的单原子进行了观察。近年来，对这些复合薄膜的电阻和磁化强度进行了测量，以阐明其物理性质。MgO-Au和MgO-Pd复合膜在-150 ~ 250 C温度范围内的电阻率为负温度系数，其行为可以用“活化隧穿模型”来解释。用SQUID测量了MgO-Fe复合膜在极低温下的磁化强度，并证实了自旋玻璃的形成。