First-principles study of ultrathin magnetic Mn films on W surfaces. II. Surface diffusion

Abstract

The atomic diffusion in the first stages of the growth of ultrathin Mn films deposed on W substrates has been investigated in the framework of the density functional theory. The most stable adsorption sites and the activation energy barriers associated to the elementary dynamical processes occurring during the diffusion of Mn adatoms on clean and Mn-covered W(100) and W(110) surfaces have been determined. The Mn surface diffusion is governed by the hopping from stable adsorption sites to nearest-neighbor positions while exchange with underlying surface atoms is rather unlikely due to much higher energy barriers. The comparison between magnetic and nonmagnetic calculations reveals the strong influence of magnetism both on adsorption sites and diffusion properties. The pseudomorphic growth of the first layers is stabilized through the magnetic interaction between adlayer and substrate atoms. Magnetism generally induces a remarkable decrease of the diffusion barriers, but an increase can also be observed in some cases for antiferromagnetic Mn films deposed on the W(110) surface, due to magnetic frustration effects.