Abstract
Two-dimensional honeycomb lattices beyond graphene, such as germanene, promise new physical properties such as quantum spin Hall effect. While there have been many claims of growth of germanene, the lack of precise structural characterization of the epitaxial layers synthesized hinders further research. The striped layer formed by Ge deposition on Ag(111) has been recently ascribed as a stretched germanene layer. Using surface x-ray diffraction and density-functional theory calculations, we demonstrate that it corresponds in fact to a surface alloy with an atomic density 6.45% higher than the Ag(111) atomic density. The overall structure is formed by stripes associated with a face-centered cubic top-layer alignment, alternating with stripes associated with a hexagonal close-packed top-layer alignment, in great analogy with the Au(111) reconstruction.
- Received 11 June 2021
- Revised 6 September 2021
- Accepted 10 September 2021
DOI:https://doi.org/10.1103/PhysRevB.104.155403
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