Unusual Strain Relaxation in Cu Thin Films on Ni(001)

Surface x-ray diffraction has been used to study the growth of thin Cu films on Ni(001). We give direct evidence for the formation of embedded wedges with internal $\{111\}$ facets in the film, as recently suggested by Müller et al. [Phys. Rev. Lett. 76, 2358 (1996)]. The unusual strain distribution within the wedges is determined and provides an explanation to the observed sudden change in growth and film morphology around 20 monolayers.