Superconductivity in some new metastable film phases

The occurrence of new metallurgical phases and enhanced superconductivity in a number of sputtered transition-metal alloy films has been studied as a function of substrate temperature during deposition. Results indicate that such new phases are readily produced in the temperature range 200–1000°C by this technique and that these new phases are accompanied by marked changes in the superconducting transition temperature. The findings show how easily the more complex transition-metal alloys, particularly σ phase, can be modified at low temperatures, and demonstrate the importance of structural instability, vis-à-vis composition, in determining the superconducting transition temperature.