Magneto-optical characterization of YBa2Cu3O7 film uniformity

Abstract
Using a magneto‐optical technique, we have nondestructively imaged macroscopic variations in magnetic flux that penetrate laser‐ablated, c‐axis oriented, epitaxial YBa2Cu3O7 superconducting films deposited on crystalline (100)SrTiO3 substrates. Flux penetration into YBa2Cu3O7 films in an externally applied magnetic field is enhanced at crystalline substrate defect sites. A relationship between flux penetration and substrate defects is experimentally demonstrated with a YBa2Cu3O7 film deposited on an intentionally degraded crystalline SrTiO3 surface.