Preparation and Structure of Artificial Superlattices of Oxides and Selenides

我们研究了人造超晶格的高质量单晶体的结构和磁性特性。高质量的单一水晶电影已经基本上生长在一个单一的水晶上。关于人工超级晶格的重要信息已经被发现如以下所示。正确地选择底层晶体、蒸发率（R_r）和底层温度（T_s）必须提高单一晶体质量的质量。例如，用蒸发岩盐对PbSe/SnSe超晶格增长的最佳条件为150 ° C的T_s和1A/s的D_r。Hile，对于增长的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。在这些最佳条件下，水晶可能由层增长机制增长，以及单体控制超级晶格中的结果。克里斯塔林的质量估计来自一个岩石曲线，明显地变得更高，具有退化层t ... More PbSe/SnSe和CoO/NiO超晶格的hickness。这似乎很可能是因为一个preudomorphous crystal下面的临界厚度增长在一个基底crystal和不匹配的每个层都被吸收为同源弹性应变。当每个层的厚度都很大时，界面会包含不合适的分散和紧张。Superlattices （PbS）_m（SnSe）_n具有m6<equal or less than>， n&gt;（2/3）_m的SnSe类型结构，m4<equal or less than>， n&lt;（2/3）_m的PbSe类型结构，以及每个层中的PbSe和SnSe结构m&gt;12， n&gt;4，响应。（CoO）_m（NiO）_n superlattices stacked with （111） plane show a well-defined magnetic peak in neutron Diffraction pattern。“超级晶格的磁性轴最可能是在电影平面上的。”（CoO）_m（NiO）_n与m， n <equal or less than>8给了一个独特的T_n类似于单相材料。However， （CoO）_m（NiO）_n超晶格与m， n <greater than or equal>20具有不同Neel温度的两个磁性相位。Less（低）

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