Observations of Flux Penetration in High-Temperature Superconductors Using Magneto-Optical Effect of EuO Layer

Fenomagnetic oxide EuO is a promising candidate for magneto-optical layer to investigate the flux penetration in high-temperature superconductors. EuO has the Curie temperature of 69K. Au film of 1 μm was deposited on EuO film as a reflection and protection layer. The magnetic moments of Eu2+ were ordered in plane. We have succeeded for the first time in observing the magneto-optical images of distribution of magnetic flux in NdBa2Cu3O7-δ single crystal using EuO film, at 5K up to 5.5T and at 60K up to 2.2T.