TY - JOUR
T1 - Striped, honeycomb, and twisted moiré patterns in surface adsorption systems with highly degenerate commensurate ground states
AU - Elder, K. R.
AU - Achim, C. V.
AU - Granato, E.
AU - Ying, S. C.
AU - Ala-Nissila, T.
PY - 2017/11/29
Y1 - 2017/11/29
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=85038878471&partnerID=8YFLogxK
U2 - 10.1103/PhysRevB.96.195439
DO - 10.1103/PhysRevB.96.195439
M3 - Article
AN - SCOPUS:85038878471
VL - 96
SP - 1
EP - 16
JO - Physical Review B (Condensed Matter and Materials Physics)
JF - Physical Review B (Condensed Matter and Materials Physics)
SN - 2469-9950
IS - 19
M1 - 195439
ER -