Adsorbed overlayers frequently exhibit degenerate, ordered ground states. We consider here the shrinking of an ordered domain that is completely embedded in an ordered domain of another phase. Two triangular lattice gases with nearest-neighbor repulsion were simulated at zero temperature with use of Monte Carlo methods. In one case, the next-nearest-neighbor interaction is taken to be zero; and in the other, the next-nearest-neighbor interaction is taken to be attractive and equal in magnitude to the nearest-neighbor repulsion, which is extant in both cases. We find that, in the first case, the number of particles in the embedded domain decreases linearly with time until the domain disappears, whereas, in the second case, the embedded domain shrinks initially, but after some time the size remains constant. The shape of the domains in the first case is approximately circular throughout the simulation runs, but in the second case the final shape is approximately hexagonal. We present a continuum analysis for the first case in which there is only nearest-neighbor repulsion, and we note that the trapping of defects at the boundary is responsible for the freezing of domain shrinkage in the second case. We conclude that a study of embedded-domain shrinkage at low temperatures can yield information concerning the microscopic details of the interactions between the particles in the adsorbed layer. Our study also demonstrates that domain freezing can occur even though there are no domain-wall intersections to pin the growth.

• Received 17 July 1990

DOI:https://doi.org/10.1103/PhysRevB.43.11438