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

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 mic roscopy (HRTEM). From HRTEM, we found that this him exhibits a Ll(0)-type o rder, characterised by a stacking of almost pure cobalt and pure platinum p lanes 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 [0 01] direction. (C) 2001 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.