Chemical long-range ordering in a CoPt alloy film grown by molecular beam epitaxy Original Research Article

The chemical long-range ordering in a CoPt alloy film, grown at 800K onto a MgO (001) substrate by molecular beam epitaxy, has been investigated using both X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). From HRTEM, we found that this film exhibits a L10-type order, characterised by a stacking of almost pure cobalt and pure platinum planes along the tetragonal axis parallel to the growth direction. The value of the long-range order parameter deduced from XRD, significantly smaller than 1, is attributed to the existence of antiphase boundaries along the [001] direction.