Effect of intermolecular interactions on the nucleation, growth, and propagation of like-spin domains in spin-crossover materials

Abstract

The nucleation, growth, and propagation of like-spin domains in spin-crossover materials was investigated during the relaxation process of a metastable HS state at low temperature using an electroelastic model running on a deformable two-dimensional square lattice. We distinguish the onset of patterns formation of low-spin domain as the intermolecular interaction is increased, passing successively through random dispersion to clustering pattern and ending up with an impressive single macroscopic domain growth. Attaining and maintaining a single-domain configuration through the transition is attributed to the long-range character of interactions. Qualitative investigation of the elastic energy, of the propagation of the low-spin domain, and of the displacement field are presented. We demonstrate that as the intermolecular interaction increases the propagation of the like-spin domain slowdown. The deformations are believed as the prolonged effect of the intermolecular interactions that are at the origin of the onset of dispersed, poly-, and single-domain nucleation. Spatial autocorrelation of the deformations analysis based on Moran's $I$ index is used. We demonstrate that at short distance significant spatially autocorrelated patterns are detected, and the extent of the autocorrelation decreases with the distance.