Quasiperiodic potassium adlayer on decagonal Al-Ni-Co quasicrystal

Area of Science:

• Materials Science
• Surface Science
• Condensed Matter Physics

Background:

• Quasiperiodicity is a key characteristic of quasicrystals, materials with long-range order but lacking translational symmetry.
• Understanding adatom behavior on quasicrystal surfaces is crucial for exploring their unique electronic and physical properties.

Purpose of the Study:

• To investigate the formation and structure of potassium (K) monolayers on the tenfold surface of decagonal aluminum-nickel-cobalt (Al-Ni-Co) quasicrystals.
• To elucidate the role of substrate-adsorbate interactions in driving quasiperiodic growth patterns.

Main Methods:

• Scanning Tunneling Microscopy (STM) for atomic-scale surface imaging.
• Low Energy Electron Diffraction (LEED) for structural analysis and symmetry determination.
• Density Functional Theory (DFT) calculations to model adsorbate-substrate interactions and predict growth structures.

Main Results:

• Demonstrated the formation of a quasiperiodic potassium monolayer on the decagonal Al-Ni-Co surface.
• Observed dispersed K adatoms at low coverage, coalescing into pentagonal and decagonal motifs at higher coverages.
• LEED patterns confirmed decagonal symmetry, and STM results closely matched DFT predictions of K adatoms binding to favorable quasiperiodic sites.

Conclusions:

• Potassium adatoms form quasiperiodic monolayers on decagonal Al-Ni-Co quasicrystals, driven by adsorbate-substrate interactions.
• The electronic structure of the quasicrystal substrate dictates the quasiperiodic growth of the potassium adlayer.
• Experimental findings are in strong agreement with theoretical predictions, validating the DFT model.