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

• We calculate Meissner ac susceptibility of square film as a function of Pearl length.
• New technique is developed for determining London penetration depth of square films.
• The technique does not require special instrumentation and complex calculations.
• Intrinsic and applied superconducting properties may be studied for the same film.

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.