Stability properties of indium doped TbFe amorphous films for magneto-optic memory applications

The stability of Indium doped TbFe amorphous films is investigated. These TbFeIn films show strong resistance to oxygen diffusion. The indium is considered to act on a thin surface layer of Tb and Fe oxides, making it a passive oxide layer. Gradual increase of saturation magnetization with aging can be explained by preferential Tb oxidation caused by oxygen diffusion increases near the film surface. An oxygen diffusion coefficient of 5 × 10
^-23
m
²
/sec is obtained for the TbFeIn films after 2,000 hours aging at 70°C and 85 % R.H. This value is lower by at least a factor of hundred as compared to TbFe films.