SUPERCONDUCTING COMPOSITION COMPRISING LN-TH-CU-O, WHEREIN LN IS PR, ND, PM, SM, EU, GD, ER OR MIXTURES THEREOF

A superconducting structure is formed in such a manner that at least an insulating layer (30) is sandwiched between two superconductor layers (10, 20) but the superconductor layers are electrically coupled with each other, and a superconducting device including the superconducting structure is constructed so as to perform a switching operation for an electric signal, to detect a light signal, and to detect the intensity of a magnetic field. Another superconducting device is formed so that two superconductor layers (3, 12) are put in direct contact with each other, and a tunnel current between the superconductor layers can be controlled. Further, a superconductor structure is formed which includes a plurality of superconductor layers and has a superconducting transition temperature or superconducting critical current higher than that of each superconductor layer, and a superconducting device including this superconducting structure can operate at a relatively high temperature. Furthermore, a superconducting circuit device is formed which can emit a coherent electromagnetic wave having a wavelength of the order of 10 mu m on the basis of the difference in energy gap between adjacent superconductor layers (22, 23). Additionally, novel oxide superconductor materials are disclosed.