Striped, honeycomb, and twisted moiré patterns in surface adsorption systems with highly degenerate commensurate ground states

K. R. Elder*, C. V. Achim, E. Granato, S. C. Ying, T. Ala-Nissila

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)
214 Downloads (Pure)

Abstract

Atomistically thin adsorbate layers on surfaces with a lattice mismatch display complex spatial patterns and ordering due to strain-driven self-organization. In this work, a general formalism to model such ultrathin adsorption layers that properly takes into account the competition between strain and adhesion energy of the layers is presented. The model is based on the amplitude expansion of the two-dimensional phase field crystal (PFC) model, which retains atomistic length scales but allows relaxation of the layers at diffusive time scales. The specific systems considered here include cases where both the film and the adsorption potential can have either honeycomb (H) or triangular (T) symmetry. These systems include the so-called (1×1), (3×3)R30â, (2×2), (7×7)R19.1â, and other higher order states that can contain a multitude of degenerate commensurate ground states. The relevant phase diagrams for many combinations of the H and T systems are mapped out as a function of adhesion strength and misfit strain. The coarsening patterns in some of these systems is also examined. The predictions are in good agreement with existing experimental data for selected strained ultrathin adsorption layers.

Original languageEnglish
Article number195439
Pages (from-to)1-16
JournalPhysical Review B
Volume96
Issue number19
DOIs
Publication statusPublished - 29 Nov 2017
MoE publication typeA1 Journal article-refereed

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