Quenched molecular dynamics simulations were made of the vacancy behavior near to the surface of an ordered CoPt alloy. The formation, migration and activation energies were deduced for various atoms (Co and Pt), moving in and between the different planes parallel to the surface. The migration of an adatom at the surface was also studied. The alloy surface was preferentially a Pt plane. There were typically two planes where the migration and formation energies were different from the bulk. The anisotropy of the structure involved an anisotropy of the diffusion. The values of the energies obtained for the different processes were used to understand the chemical ordering in CoPt(001) thin films grown at different temperatures. These films presented indeed a concentration modulation along the growth direction with 2 temperature ranges. This behavior was analyzed in terms of chemical ordering using a classical phenomenological diffusion law with the values of the energies deduced by quenched molecular dynamics.

Diffusion Piloted Ordering in Co-Deposited CoPt Epitaxial Layers: Experiment and Quenched Molecular Dynamics Simulations. Ersen, O., Goyhenex, C., Pierron-Bohnes, V.: Physical Review B, 2008, 78[3], 035429