Effect of sputtering power on the magnetic properties of amorphous perpendicular TbFeCo films

A series of amorphous perpendicular TbFeCo films are sputtered using a composite target. The magnetic properties of the TbFeCo films are found to strongly be influenced by sputtering power. The above-RT magnetic compensation point in the films sputtered at high powers is revealed by thermomagnetic measurements. With increasing the power the compensation point shifts considerably towards higher temperature, while only a slight reduction in the Curie temperature occurs. The coercivity is found to initially increase with the power and then falls, which is in accordance with film composition moving from FeCo-rich to Tb-rich side. This can be well explained by the sputtering yield of Tb, which increases faster than FeCo atoms with the power during the sputtering. Our results show a convenient way to adjust the coercivity of the films by modifying the Tb-to-FeCo ratio using the sputtering power.