Observation of Flux Density Distribution in YBa2Cu3Ox Superconductor Thin Film Using Bi-Substituted Iron Garnet Film

Bi-substituted iron garnet film with a large Faraday rotation and perpendicular magnetization was prepared, and the film domain patterns were used to observe the flux penetrating superconducting YBa
2
Cu
3
O
x
thin films. Observations were performed for both square and disk-shaped YBa
2
Cu
3
O
x
films. The penetration behavior depends on defects and the shape of the film. We confirmed that the flux density in superconducting film as observed through the iron garnet film domain patterns was nearly the same as that estimated from the sample magnetization.