Perpendicular magnetic anisotropy of Tb‐Co amorphous films sputtered in H2‐added Ar gas

Very large perpendicular magnetic anisotropy has been observed in Tb‐Co amorphous films deposited by nonbiased rf sputtering using H2‐added Ar gas. As the hydrogen partial pressure of the gas increases, the perpendicular anisotropy constant Ku increases remarkably and rectangular Kerr hysteresis loop appears. For 10% H2, Ku reaches near 105 J/m3, which is sufficient to direct the magnetization perpendicular to the film plane. These films can be used as magneto‐optical recording media because of the relatively large Kerr rotation angle and coercive force. The mechanism of increasing Ku remains to be clarified.