Soft magnetic and structural properties of (FeCo)–(AlSi) alloy thin films

The dependences of static and dynamic magnetic properties on both substrate deposition temperature (TS) and film-thickness (d) for (FeCo)-(AlSi) alloy thin films are discussed in conjunction with structure. The samples of a multi layered type (FeCo)-(AlSi) alloy thin films were fabricated at Ts by DC sputter-deposition onto (1 0 0) MgO substrates by using two targets of Fe75Co25 and Al50Si50. For the first time, the DO3 phase in the quaternary alloy films are realized for TS at around 400 ℃ with d larger than 25 nm. The order parameter (S) was estimated by taking into account crystal structure factor, absorption factor, multiplicity factor, temperature factor, and Lorentz polarization factor. It is found that S increases with d, becoming nearly 1 for d larger than 50 nm. Observations by high resolution transmission electron microscopy support this result. The coercivity (Hc) and effective damping parameter (αeff) decrease with increasing d and remain nearly constant, approximately 4 Oe and 5 × 10−3, respectively. The result that HC decreases with increasing S suggests that (FeCo)-(AlSi) thin films with the DO3 phase are an attractive candidate for future high frequency device applications.