Monte Carlo Metropolis study of cluster evolution in spin-crossover solids within the framework of a mechanoelastic model

Abstract

In this paper we apply a standard Monte Carlo Metropolis procedure for the treatment of a mechanoelastic model, in order to study the evolution of clusters in open boundary hexagonal spin-crossover systems, composed of molecules in a triangular lattice and linked by springs. The temperature-driven transition between the paramagnetic high-spin phase and the diamagnetic low-spin phase is reproduced by taking into account the lattice elastic energy change in addition to the energy variation of spin-active molecules. This method allows us to determine where higher amounts of energies are stored and where the spins are more probable to flip and to form clusters. The spreading of clusters from the corners, similar to recently published experimental data, is well reproduced. We also analyze here the lattice deformation during the transition and we show that the deformation increases as the spring constant diminishes. A systematic comparison with results obtained in the framework of our previous Arrhenius approach of the mechanoelastic system is provided.