Al nanostructures on quasicrystalline Al-Pd-Mn

The growth and structure of vapor-deposited Al textures on the pentagonal surface of the Al-Pd-Mn quasicrystal are monitored as a function of the substrate temperature between 200 and 300 K. We observe two distinctly different growth modes. In the high-temperature growth regime, five Al domains grow in the face-centered cubic structure sharing their 〈1 1 1〉 and 〈1 0 0〉 axes with the 3-fold- and 2-fold-symmetry directions of the icosahedral substrate, respectively. We argue that interdiffusion of adsorbate atoms induces a domain orientation that maximizes the coincidence of symmetry elements between the cubic and the icosahedral structure. A fundamental geometric affinity on a local scale between the periodic and the aperiodic structure leads us to a plausible atomistic interface model which accounts for the experimental observations. Below 250 K, diffusion into the substrate is limited so that the growing film only locks to the topmost substrate layer and develops in five Al domains with their [1 1 1] axes predominantly aligned parallel to the 5-fold-symmetric surface normal.