Physical Properties of Artificial Metallic Superlattices

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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.