ORALS

Quasiperiodic structures exhibit long-range order like normal crystals but they lack translational symmetry. Quasicrystals were first discovered as a new class of intermetallic compounds, now comprising hundreds of members in binary and ternary systems. They usually adopt either the icosahedral or the decagonal point group symmetry. The discovery of quasicrystals has led to a paradigm shift in crystallography and has attracted a large interest in the material science community, motivated by unexpected physical properties that could be linked to quasiperiodicity. This remarkable class of materials has also challenged our understanding of metal surfaces. An atomic scale description of their surfaces is especially important, as it forms the basis for understanding and predicting phenomena such as gas adsorption, metal epitaxy, and friction. Of interest also are studies of nucleation and growth of metal thin films on quasicrystalline surfaces, demonstrating that local pseudomorphic growth can occur due to preferred adsorption of the metal ad-species at specific sites of the surface quasilattice. The idea is that the complex potential energy surface of quasicrystalline surfaces could serve as a template to grow new 2D quasicrystalline systems. Here, we will review the different results obtained along this direction, from local peudomorphic growth of Al starfish islands on the 5-fold surface of the icosahedral i-Al-Cu-Fe quasicrystal [1] to pseudomorphic single layer high islands in the case of Ag/5f-Al-Pd-Mn [2] and up to the formation of complete 2D quasiperiodic metal layers (Pb, Bi or Sn) templated on various quasicrystalline surfaces [3]. Self-organized molecular films with long-range quasiperiodic order could also been grown by using the complex potential energy landscape of quasicrystalline surfaces as templates. The long-range order arises from a specific subset of quasilattice sites acting as preferred adsorption sites for the molecules, thus enforcing a quasiperiodic structure in the film [4]. Finally we will show some recent examples of 2D quasicrystalline oxide layers obtained by reduction of ABO3 perovskite thin films grown on Pt(111) [5,6].

References:
[1] T.A. Cai et al., Surface Science, 526 (2003) 115-120.
[2] B. Unal et al., Phys. Rev. Lett., 102 (2009) 196103.
[3] J. Ledieu et al., PRB Rapid Comm., 77 (2008) 073409.
[4] V. Fournée et al., ACS Nano, 8 (2014) 3646–3653.
[5] S. Förster et al., Nature, 502 (2013) 215–218.
[6] C. Ruano M. et al., Phyc. Chem. Chem. Phys., 24 (2022) 7253.