Magnetic properties and microstructure of FePt/GePt bilayer

We explored the island-like Ge3Pt2 underlayer effect and post-annealing temperature on FePt magnetic properties and microstructure. The growth stress between Ge3Pt2 and quartz. After island-like underlayer, the L1(0) FePt film was deposited on Ge3Pt2 islands or quartz substrate simultaneously. After deposition, the GePt/FePt bilayer post-annealing at 400 degrees C for 1 h, the higher degree of ordering (S = 0.86) and coercivity (H-c = 8.8 kOe) than single layer FePt film (H-c = 6.4 kOe) were measured. This suggests that there is a surface morphology dependence on the coercivity of FePt film. During post-annealing, the island-like Ge3Pt2 induced tensile stress on FePt, which enhanced the formation of ordered FePt. In comparison, when the post-annealing up to 800 degrees C for 1 h, the FePt ordering was suppressed (S = 0.75) and the coercivity was down to 3.6 kOe. It is due to the interface diffusion between GePt and FePt at 800 degrees C. The irregular isolated GePt/FePt islands were formed on quartz substrate. As a result, the Ge3Pt2 compound was good for underlayer of FePt film with low post-annealing temperature (400 degrees C). (c) 2006 Elsevier B.V. All rights reserved.