The dependences of magnetic properties and effective damping parameter (αeff) on film-thickness (d) and growth temperature (Ts) for Fe69Co26Si5 alloy films are investigated. The saturation magnetization (Ms) are found to decrease from approximately 1,700 to 1,500 emu/cm3 with d for Ts = 230 °C. For 40 nm films, the magnetization remains constant over the entire range of Ts from 35 to 360 °C. The coercivity (Hc) values for Ts above 120 °C are approximately 20 Oe. Those films deposited at Ts =120 °C or higher are epitaxial with the relation of FeCoSi//MgO in the film plane. For the films deposited at Ts =230 °C, the αeff rapidly decreases, and then slightly increases with d. The minimum αeff value of 0.002 is obtained at Ts = 230 °C.
