Critical Currents in Superconducting Tin and Indium

The critical current densities in planar superconducting films of tin and indium were determined as a function of temperature by using a new method. An alternating current in a flat ribbon-shaped drive loop was imaged in the superconducting film. Both tin and indium films were deposited at 80^∘{}K and were annealed to temperatures between 80 and 180^∘{}K. The temperature dependence of Jc(t) was found to be (1-t²)^α(1+t²)1/2, where α=1.23 for tin and α=1.16 for indium.