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 H2gas is added to Ar sputtering gas. Ku in Tb-Fe films decreases with increasing H2partial pressure, while Ku in Tb-Co films increases and reaches almost 10⁶erg/cm³. The internal stress in the films changes slightly with increasing H2partial pressure. Consequently, the change in Ku can not be explained in terms of magnetostriction. Mass spectroscopy shows that those films sputtered in H2-added Ar gas contain H2about three times more than those sputtered in pure Ar gas. It is likely that H2induces 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.