Tutorial on the elastic theory of spin crossover materials

Abstract

In this paper, we present the ingredients that allow the building-up of the elastic model, one of the approaches that successfully describes the phenomena observed in complex spin-crossover systems at both the micro- and macroscopic level and we review its challenges and some of its main applications. After discussing the usefulness and the drawbacks of some of the previous models (such as mean-field and Ising-like ones), we introduce the premises that imposed the elastic approach in the study of spin-crossover compounds and present the steps to follow in order to build-up and implement the model. As illustrative applications, we first discuss the simulations of relaxation, thermal transition, and the nucleation phenomena and then introduce the effects of anisotropy in two-dimensional systems. Special sections are dedicated to particular structures like three-dimensional, spin-crossover micro- or nanoparticles as layers on substrates or embedded in polymer or surfactant matrices as well as to the study of ultra-fast phenomena.