Perpendicular Magnetic Anisotropy of Tb-Co Amorphous Films Sputtered In H2-Added Ar Gas

Tb-Co amorphous films are prime candidates for use as magneto-optical recording media, but the method commonly employed to induce a perpendicular magnetic anisotropy, bias sputtering, is not compatible with glass substrates. In this case RF sputtering is used in an H
2
-Ar gas mixture, without a substrate bias voltage, to form Tb-Co films. As the hydrogen partial pressure P
H2
was increased, the film saturation magnetization M
s
decreased, the uniaxial anisotropy constant K
u
increased, and the Kerr hysteresis loop became more rectangular. For P
H2
= 10 percent, samples had an extremely large positive anisotropy even when the Tb content was varied over a wide range.