Contactless testing of mercury-based thin films

We describe a non-destructive and contactless measuring method for characterization of thin HTS superconducting layers. To demonstrate the capability of the method we measured two types of mercury-based samples prepared by two different methods. The precursor film was placed either on the mercury source (contact mercuration) or it was placed close to the mercury source without contacting it (contactless mercuration). Magnetization currents in the sample were induced by the external magnetic field. Then, the magnetic field produced by these magnetization currents was measured using micro Hall probes. From the shape of the profile and its amplitude we determined the kind of the currents (inter or intragranular), their uniformity, electric field–current density curves and the critical currents. The described method does not require any electrical contacts on the sample and it makes the preparation of the sample for the measurements very easy. Also a possible damage of the sample due to the contact technology can be avoided.