EuSe as magneto-optical active coating for use with the high resolution Faraday effect

The high resolution Faraday effect requires a magneto-optical active thin film coating for observations of penetrated flux in superconductors. The use of EuSe for this coating offers many advantages, such as better handling during the evaporation process and a higher achievable contrast compared to the 'classical' mixture of EuS and EuF₂. In this paper the apparatus is described and the conditions discussed for achieving optimal thickness of the magneto-optical layer. This technique was used for observations of penetrating flux in niobium and in the high T_c superconductors YBa₂Cu₃O_7-δ (single crystals, sintered specimens and epitaxial thin films) and Bi₂Sr₂CaCu₂O_8-δ single crystals.