Reducing treatment effects on the magneto-optical properties of Ca-doped YIG films

The change of the lattice constant, the absorption loss and Faraday rotation due to reduction of Ca:YIG films are investigated. It was found that the absorption loss of the reduced Ca:YIG films at 1.15 µm is 2∼3 dB/cm irrespective of the content of Ca,Pb,Pt ions and the vacancies, and the Faraday rotation increased in the near infrared region and decreased in the visible region. It turns out that the reduction of Pb⁴⁺→ Pb²contributes to the change of lattice constant, and that of Fe⁴⁺→ Fe³⁺to the change of absorption loss. The large absorption loss in as-grown Ca:YIG films is seems to be due to the electronic transitions of Fe⁴⁺absorption centers associated with or without oxygen vacancies.