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 $J_c\mathrm{}\left(t\right)\mathrm{}$ was found to be ${(1-t^2)}^{\alpha }{(1+t^2)}^{\frac{1}{2}}$, where $\alpha =1.23\mathrm{}$ for tin and $\alpha =1.16\mathrm{}$ for indium.