Diffusion of Fe atoms on clean W(100) and W(110) as well as on Fe/W(100) and Fe/W(110) surfaces was investigated by means of exhaustive first-principle calculations. Comparison of the activation energy barriers obtained for hopping and exchange migration processes showed that the surface diffusion proceeds via jumps to the nearest

sites. The activation energies were higher for Fe adatom on clean W than those for Fe adatoms moving on Fe-covered W. The magnetism of the underlying Fe/W(100) films has a pronounced influence on the diffusion, as evidenced not only by a reduced activation energy barrier but also by a change of the stable adsorption place. Fe atoms reaching step edges were trapped there and eventually diffuse along the steps more slowly than the adatoms on the terraces. The rate of diffusion increased upon depositing a row of Fe atoms along steps.

Diffusion Mechanisms for Iron on Tungsten. D.Spišák, J.Hafner: Surface Science, 2005, 584[1], 55-61