Low-temperature growth of perpendicular FePt films

L1₀ FePt films with high perpendicular coercivity were successfully fabricated by using Cr₆₅Mo₁₅Mn₂₀ underlayers with subsequent forming gas (Ar 95% + H₂ 5%;) annealing. To adjust the strain energy and the orientation of FePt, Fe and Pt intermediate layers were used. Samples annealed at 275°C with thin Pt layers (<5 nm) show relatively small coercivity due to the stabilizing effects from the underlayers. With the increasing thickness of Pt, the strain was locally released and the (111) grains appeared. The nucleation of the ordered L1₀ FePt phase accompanied the formation of the FePt (111) phase, resulting in a high coercivity but deteriorated perpendicular anisotropy. To maintain the [001] preferred orientation with high coercivity, the sample with a 3.5-nm Pt layer was annealed at 350°C. The coercivity as high as 8400 Oe was realized.