Quasiperiodic potassium adlayer on decagonal Al–Ni–Co quasicrystal
Quasiperiodicity in free-electron-like metals is a subject of significant interest within the scientific community. In this work, utilizing scanning tunneling microscopy (STM), low energy electron diffraction (LEED), and density functional theory (DFT), we demonstrate the formation of a quasiperiodic potassium monolayer on the tenfold surface of decagonal Al–Ni–Co quasicrystal. A dispersed growth comprising of isolated K adatoms is observed at sub-monolayer coverage, which coalesce with increasing coverage and forms pentagonal and decagonal quasiperiodic motifs. LEED demonstrates distinct rings of spots displaying decagonal symmetry. Furthermore, our DFT calculation using the W-approximant surface that closely resembles d-Al–Ni–Co shows that sizable adsorbate-substrate interaction makes the potassium adatoms bind to the quasiperiodically dispersed favorable adsorption sites resulting in the formation of quasiperiodic potassium monolayer. Notably, the experimental motifs obtained from STM measurements align remarkably well with the DFT predictions, underscoring the intricate relationship between the electronic structure of the substrate that drives the quasiperiodic growth of the potassium adlayer.