Perpendicular anisotropy in Tb-Fe and Tb-Co amorphous films sputtered in H2-added Ar gas

It has been found that the perpendicular anisotropy Ku in amorphous Tb-Fe and Tb-Co films prepared by rf sputtering changes remarkably when H 2 gas is added to Ar sputtering gas. Ku in Tb-Fe films decreases with increasing H 2 partial pressure, while Ku in Tb-Co films increases and reaches almost 106erg/cm3. The internal stress in the films changes slightly with increasing H 2 partial pressure. Consequently, the change in Ku can not be explained in terms of magnetostriction. Mass spectroscopy shows that those films sputtered in H 2 -added Ar gas contain H 2 about three times more than those sputtered in pure Ar gas. It is likely that H 2 induces change in microstructure in films causing large change in Ku. However, the mechanism and the reason for different behaviors between Tb-Fe and Tb-Co are not clear yet.