Surface X-ray diffraction analyses were carried out on the geometrical structure of a 13-monolayer thick Fe film on W(110). The Fe adlayer was characterized by a well-ordered 2-dimensional array of misfit dislocations that had a periodicity of 35.84 and 50.76Å along the [001] and [¯110] directions, respectively. On the (110) plane, the average Fe structure was isotropically strained by +1.2% with respect to (bulk) body-centered cubic Fe; corresponding to lattice constants of 2.901Å along [001] and 4.103Å along [¯110]. In the surface normal direction, [110], it was found that the Fe film was also strained by +0.22% (c = 4.062Å). This corresponded to a slightly laterally distorted body-centered tetragonal phase with a = b = 2.887Å, c = 2.901Å and γ = 89.4°. The intensity distribution along 14 satellite rods was analyzed quantitatively by using a sine-wave modulation ansatz for the lateral and vertical displacements of the Fe atoms out of their average positions. Maximum amplitudes of the order of 0.7Å were found for the normal and lateral modulations. The modulation amplitudes continuously decreased with distance from the Fe/W(110) interface. The adlayer/substrate registry was characterized by a 37/34 coincidence between the Fe and W atoms; where the vertical Fe corrugation was directly related to the Fe-adsorption site.

Surface X-Ray Structure Analysis of Periodic Misfit Dislocations in Fe/W(110). R.Popescu, H.L.Meyerheim, D.Sander, J.Kirschner, P.Steadman, O.Robach, S.Ferrer: Physical Review B, 2003, 68[15], 155421 (11pp)