权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Preparation and Structure of Artificial Superlattices of Oxides and Selenides

氧化物和硒化物人工超晶格的制备和结构

基本信息

批准号：
61470045
负责人：
BANDO Yoshichika
金额：
$ 2.37万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

项目摘要

We have investigated the structural and magnetic properties on thigh quality single crystals of the artificial superlattices. High quality single crystal films have been epitaxially grown on a single crystal by the evaporation. Important informations on the artificial superlattices have been obtained as follows.1. Proper selection of substrate crystals, evaporation rates (R_r), and substrate temperatures (T_s) must be taken for growth of good quality single crystals. For example, optimum conditions for growth of PbSe/SnSe superlattice on the rock salt by evaporation are T_s of 150゜C, and D_r of 1A/s. Hile, optimum conditions for growth of C0O/NiO superlattice on sapphire c plane by the reactive evaporation are T_s of 200゜C and D_r less than 1 A/s. Under these optimum conditions, the crystal may grow by layer growth mechanism, and results in the monolayer controlled superlattice.2. The crystalline quality estimated from a rocking curve significantly become higher with decreasing layer t … More hickness in PbSe/SnSe and CoO/NiO superlattices. It seems likely that a preudomorphous crystal below a critical thickness grows on a substrate crystal and the mismatch is adsorbed in each layer as homogeneous elastic strain. When each layer thickness is large, the interface contains the misfit dislocations and strain.3. The superlattices (PbS)_m(SnSe)_n have the SnSe type structure for m<equal or less than>6, n>(2/3)_m, the PbSe type structure for m<equal or less than>4, n<(2/3)_m, and the PbSe and SnSe structures in each layer for m>12, n>4, respectively.4. (CoO)_m(NiO)_n superlattices stacked with (111) plane show a well-defined magnetic peak in neutron diffraction pattern. The magnetic axis of the superlattices is most probably oriented within the film plane. The (CoO)_m(NiO)_n with m, n <equal or less than> 8 gives a unique T_n like a single phase material. However, (CoO)_m(NiO)_n superlattices with m, n <greater than or equal> 20 have two magnetic phases with different Neel temperatures. Less

我们研究了高质量人工超晶格单晶的结构和磁性。用蒸发法在单晶体上外延生长了高质量的单晶薄膜。在人工超晶格的研究中获得了以下重要信息：1.为了生长出高质量的单晶，必须选择合适的衬底晶体、蒸发速率（R_r）和衬底温度（T_s）。例如，在岩盐上蒸发生长PbSe/SnSe超晶格的最佳条件是T_s为150 ℃，D_r为1A/s。同时，用反应蒸发法在蓝宝石c面上生长CoO/NiO超晶格的最佳条件为：T_s = 200 ℃，D_r <1 A/s。在此最佳条件下，晶体可按层生长机制生长，形成单层控制的超晶格.从摇摆曲线估计的结晶质量随着层t的减小而显著变高 ...更多信息 PbSe/SnSe和CoO/NiO超晶格中的厚度。这似乎是一个predomorphous晶体低于临界厚度生长在衬底晶体和失配是吸附在每一层均匀的弹性应变。当各层厚度较大时，界面处存在失配位错和应变.（PbS）_m（SnSe）_n超晶格在m <equal or less than>6，n>（2/3）_m时具有SnSe型结构，在m <equal or less than>4，n<（2/3）_m时具有PbSe型结构，在m>12，n>4时每层分别具有PbSe和SnSe结构. (CoO)m（NiO）n超晶格在（111）晶面上的中子衍射图显示出一个清晰的磁峰。超晶格的磁轴很可能在薄膜平面内取向。（CoO）_m（NiO）_n（m，n <equal or less than>= 8）具有单一的T_n，类似于单相材料.而（CoO）_m（NiO）_n（m，n = 20）超晶格<greater than or equal>具有两个不同Neel温度的磁相。少