Perpendicular anisotropy in Tb-Fe and Tb-Co amorphous films sputtered in H<inf>2</inf>-added Ar gas

Abstract

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 <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> gas is added to Ar sputtering gas. Ku in Tb-Fe films decreases with increasing H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> partial pressure, while Ku in Tb-Co films increases and reaches almost 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> erg/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . The internal stress in the films changes slightly with increasing H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> partial pressure. Consequently, the change in Ku can not be explained in terms of magnetostriction. Mass spectroscopy shows that those films sputtered in H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> -added Ar gas contain H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> about three times more than those sputtered in pure Ar gas. It is likely that H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> 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.