The High Resolution Magneto-Optical Faradayeffect As A Research Tool to Investigate Details of Current and Magnetic Flux Distribution in Y-Ba-Cu-O Thin Films

The magneto-optical Faradayeffect [MOFE] is known to be an excellent tool for the spatially resolved analysis of the flux distribution in superconductors. We use three examples to demonstrate the power of this technique for device oriented investigations. It is shown that homogeneous Yba2Cu3O7 thin films with different shape show a flux pattern strongly depending on the geometry of the sample; model calculations for the flux distribution are in excellent agreement with the experimental results. Furthermore, we show, that crystallographic defects as well as imperfections due to pattern delineation are affecting the flux pattern on macroscopic scale. In a third example we use the MOFE to demonstrate that pulsed laser irradiation of Yba2Cu3O7 thin films with UV photons of moderate flux causes an enhancement of the critical current.