40 nm thick CoPt and FePt films were prepared on oxidized Si substrates wit
h 10 nm MgO underlayers. The maximum coercivity (H-c) for CoPt films was fo
und to be similar to 10 kOe after annealing at 700 degreesC for similar to
20-30 minutes (min). Structural analysis showed a significant amount of FCC
phase as well as the ordered L1(0) phase in these films. FePt films showed
an abrupt increase of ordered volume fraction and H-c in the initial stage
of annealing and predominance of the tetragonal L1(0) phase after 10 min.
at 700 degreesC. The maximum H-c reached similar to 16 kOe after annealing
at 700 degreesC for more than 20 minutes. Dark field (DF) images of the ann
ealed CoPt films showed individual grains which exhibited a possibility of
several variants or disordered phase with dimensions similar to the exchang
e correlation length, b(cm). The temperature dependence of H-c seems to ind
icate a weak pinning mechanism in the highly ordered FePt films. Magnetic f
orce microscopy indicated a complex domain structure consisting of clusters
with dimensions of several hundred nanometers.