Relaxation dynamics and growth modes of metastable spin-crossover materials with magnetic interactions

A two-dimensional spin-1 Blume-Emery-Griffiths (BEG) model is used to describe the relaxation dynamics of spin-crossover (SC) compounds with magnetic interactions from a metastable high-spin state by means of Monte Carlo simulations with Arrhenius dynamics. The model comprises temperature-dependent effective spin exchange interaction accounting for spin-phonon interactions. The growth modes of the stable low-spin state domains are singled out in the model parameters' space. For weak magnetic interactions, numerical results indicated a kind of 2D-nucleation with the birth, spread and coalescence of low-spin diamagnetic domains following the Becker-Doering law. A schematic growth phase diagram is presented.