Dot arrays of L10-type FePt ordered alloy perpendicular films fabricated using low-temperature sputter film deposition

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 degrees C. Then we examined the magnetic properties of the dot arrays made from these films. The uniaxial magnetic anisotropy K-u for L1(0)-type FePt films (10 nm in thickness) deposited with a Pd underlayer on MgO(001) substrates reached about 2 x 10(7) erg/cm(3) at the substrate temperature T-s of 200 degrees C, and 3 x 10(7) erg/cm(3) at T-s = 250 degrees C. The order parameter S was about 0.46 at T-s = 300 degrees C. Moreover, K-u for L1(0)-FePt films fabricated on glass disks using MgO/Cr underlayers shows 3.4 x 10(7) erg/cm(3) at T-s = 300 degrees C, which was almost equal to that for FePt single-crystal films deposited on Pd/MgO(001). The switching field distribution sigma/H-c for dot arrays made from L1(0)-FePt film [5 nm in thickness, on Pd/ MgO(001) at T-s = 250 degrees C] was small; sigma/H-c = 0.11 for a dot diameter of 15 nm. This value was smaller than that of hcp-Co75Pt25 dot arrays (sigma/H-c = 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. (C) 2011 American Institute of Physics. [doi:10.1063/1.3556697]