Using ultrahigh vacuum sputter film deposition, we fabricated L1 0-type Fe50Pt50 ordered alloy perpendicular films on MgO(001) single-crystal substrates and 2.5 in. glass disks at low substrate temperatures of 200-350°C. Then we examined the magnetic properties of the dot arrays made from these films. The uniaxial magnetic anisotropy Ku for L10-type FePt films (10 nm in thickness) deposited with a Pd underlayer on MgO(001) substrates reached about 2 10 7 erg/cm3 at the substrate temperature Ts of 200C, and 3 107 erg/cm3 at Ts 250C. The order parameter S was about 0.46 at Ts 300C. Moreover, Ku for L10-FePt films fabricated on glass disks using MgO/Cr underlayers shows 3.4 107 erg/cm3 at Ts 300C, which was almost equal to that for FePt single-crystal films deposited on Pd/MgO(001). The switching field distribution σ/Hc for dot arrays made from L10-FePt film [5 nm in thickness, on Pd/MgO(001) at Ts 250°C] was small; /Hc 0.11 for a dot diameter of 15 nm. This value was smaller than that of hcp-Co75Pt25 dot arrays (/Hc 0.18). The difference was mainly attributable to the degree of the easy axis distribution. This result demonstrates the homogeneous formation of a L10-type ordered structure in the FePt layers.
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