Preparation and magnetic properties of strontium ferrite thin films

Strontium ferrite films were deposited by RF sputtering of a commercial strontium ferrite target onto fused quartz substrates maintained at temperatures up to 900°C. Films deposited at T<800°C were amorphous, but films deposited at T>800°C had crystalline M-type strontium ferrite structures. The thin composition corresponded to that of the target. Films deposited at 800°C were partially oriented in the [110] direction with the c-axis in the plane. Postannealing led to an increase in the magnetization, indicating incomplete formation of ferrite in the as-deposited state. Both in-plane and perpendicular hysteresis loops are rectangular with remanence ratios of 0.8 and 0.6, respectively, showing partial orientation with the c-axis. The torque curve is consistent with the above, although there are some additional anomalous peaks