Detection of new superconductors using phase-spread alloy films

We describe an effective method for discovery of new superconductors, which combines phase-spread alloy thin film preparation with a magnetic field modulated (MFM) microwave absorption technique. The MFM technique can detect superconductivity in YBa2Cu3O7−δ volumes as small as 5×10−11 cm3. As an illustration, PrxGd1−xBa2Cu3O7−δ thin films with varying x were simultaneously grown on the same substrate using a phase-spread alloy technique. The onset temperature determined from the microwave absorption agrees with resistivity, Auger spectroscopy, and energy-dispersive x-ray microanalysis data. When phase-spread Lax(NiB)1−xNy films (0