Determination of London penetration depth from ac susceptibility measurements of a square superconducting thin film

Abstract

A technique is developed for determining the London penetration depth by ac susceptibility measurements of a square film. It is based on the numerical calculation of the Meissner susceptibility of square superconducting films as a function of the Pearl length and the critical-state susceptibility of thin disks previously derived analytically. With this technique, intrinsic superconducting properties may be studied for each film together with critical-current density. The application of the technique to an actual YBa2Cu3O7−δ film allows us to obtain its temperature dependent penetration depth and depairing current density.