Initial stages of heteroepitaxial Mg growth on W(110): Early condensation, anisotropic strain, and self-organized patterns

We have studied the initial stages of the heteroepitaxy of Mg on W(110) in situ, by means of complementary microscopic and spectromicroscopic techniques. In the submonolayer coverage regime the Mg film undergoes a series of structural transitions which are clearly distinguished in the diffraction pattern. Monitoring the Mg 2p core-level permits the identification of the different energy shifts associated with each superstructure. During deposition of the second Mg monolayer at moderate temperatures, the growth of single atomic height stripes is observed. The Mg 2p core level of the first (interface) and second monolayer are remarkably separated. The density, length, and width of the stripes, stabilized by the anisotropic misfit between the W(110) and Mg(0001) lattices, can be tuned by modifying the growth parameters.