  The authors developed a new analysis technique for atomic disorder structures
in full-Heusler alloys using x-ray diffraction (XRD) with Co-Ka and Cu-Ka
sources. The developed technique can quantitatively evaluate all the atomic
disorders for the exchanges between X, Y, and Z atoms in full-Heusler X2YZ
alloys. In particular, the technique can treat the DO3 disorder that cannot be
analyzed by ordinary Cu-Ka XRD. By applying this technique to full-Heusler
Co2FeSi alloy thin films formed by rapid thermal annealing (RTA),
RTA-temperature (TA) dependence of the atomic disorders was revealed. The site
occupancies of Co, Fe, and Si atoms on their original sites were 98 %, 90 %,
and 93 %, respectively, for the film formed at TA = 800 degree C, indicating
that the RTA-formed Co2FeSi film had the L21 structure with the extremely high
degree of ordering.
