Physical Properties of Artificial Metallic Superlattices

采用超高真空沉积方法，将金属元素的各种组合制备出具有人工上层结构的多层薄膜。已经证实，在各种情况下，结构能够在原子尺度上进行控制。这样就可以综合各种基础研究的模型系统。结果表明，沉积在Sb表面的Mn原子发生化学反应，形成铁磁性的MnSb复合层。如果Mn的标称厚度为1< 1>，则在Sb层之间得到外延堆积的Mn铁磁单层。容易磁化的方向是垂直于薄膜平面。作为由磁性元素组成的多层材料的例子，制备了Fe-Dy和Fe-Nd多层材料。如果单层厚度小于20< 1>，则结构为非晶态，居里温度通常低于室温。在Fe(44<Ang>-Nd（6<Ang>）中观察到有趣的自旋重取向现象；在300K时，随着温度的降低，平面内的磁化逐渐向法向方向转变。揭示了同步x射线在研究铁锰多层膜复杂结构方面的应用价值。由薄铁层和厚锰层组成的多层材料的磁性可以看作是微磁性；即弱铁磁性富铁层（非晶）通过与Mn层的反铁磁性相互作用耦合。用V与Ag或V与Si结合的方法研究了多层膜的超导性能。在临界场的温度依赖关系中观察到量纲交叉现象。在这两种情况下，转变温度都随着V层厚度的减小而降低，尽管有人猜测界面效应可能会提高转变温度。

By ultrahigh veacuum deposition method, multilayered films with artificial superstructures have been prepared from various combinations of metallic elements. It has been confirmed that structures are able to be controlled on an atomic scale in various cases. It is thus possible to synthesize model systems for various fundamental researches.It was found that Mn atoms deposited onto Sb surface react to form a ferromagnetic MnSb compound layer. If the nominal thickness of Mn is 1<Ang>, a ferromagnetic monolayer of Mn epitaxially stacked in between Sb layers is obtained. The easy direction of the magnetization is in perpendicular to the film plane. As examples of multilayers consisting of magnetic elements, Fe-Dy and Fe-Nd multilayers have been prepared. If the individual layer thickness is less than 20<Ang>, the structure is amorphous and the Curie temperature is normally lower than room termperature. An interesting spin reorientation phenomenon was observed in Fe(44<Ang>-Nd(6<Ang>; The magnetization in the plane at 300K turns gradually to the direction along the normal with the decrease of temperature.The utility of synchrotron X-ray has been revealed to study the complicated structure of Fe-Mn multilayers. The magnetic properties of multilayers consisting of thin Fe and thick Mn layers may be regarded as a mictomagnetism; i.e. weak ferromagnetic Fe-rich layers(amorphous ) are coupled through the antiferromagnetic interaction fo Mn layer.Superconducting properties of multilayers are investigated with combining V and Ag or V and Si. Dimensional crossover phenomenon was observed in the temperature dependences of critical field. In both cases, the transition temperature decreases with decrease of V layer thickness although there had been some speculation that an interface effect might raise the transition temperature.