XPS oxidation study of TbFeCo films

The oxidation of TbFeCo amorphous alloys in the temperature range 70-120°C is examined using XPS, optical and magnetic measurement techniques. As a consequence of this oxidation process, a complex structure is formed whose upper surface layer consists of oxides of Tb, Fe and Co. Below this oxidized structure (approximately 5 nm thick) is a region consisting of terbium oxide within which Fe and Co exist in their metallic states. This lower region significantly alters the magneto-optical properties of the thin films and the thickness of this region increases with annealing time. The kinetics of the process follows a parabolic law and is diffusion limited with an activation energy of 0.5±0.1 eV. The oxidation rate of TbFe is hindered by Co additions. This is not the result of Co segregation or preferential Co oxidation phenomena. © 1988.