The Effect of GePt Underlayer on the$L1_0$Ordering FePt Thin Films

We have explored the effect of GePt underlayer deposition temperature on L1₀ ordered FePt films. As the deposition temperature of GePt increased from room temperature (RT) to 800degC, the coercively (H_c) of the (GePt/FePt) bilayer increased from 1.1 to 9.1 kOe, which indicated the Ge₂Pt₃ phase formed at higher deposition temperature and promoted the L1₀ ordered FePt phase formation. Under the similar process, the single layer FePt coercively was 6.9 kOe. The interlayer diffusion between GePt and FePt cannot be avoided when the GePt underlayer deposited at RT. An interesting island-like microstructure was observed when GePt underlayer deposited at higher temperature