Coupled magnetic interactions and the Ising-like model for spin crossover in binuclear compounds

We introduced the technique of coupling of Ising-like spins in symmetric molecules in a way analogous to coupling of “real” spins known from the theory of quantum spin momentum. This new basis provides more natural and in some cases easier way of capturing the spin crossover behaviour of a binuclear system. We applied this general procedure on the simplest case of binuclear compounds where we took into account also the intramoleculear magnetic exchange interaction, which was inspected together with the intermolecular elastic cooperative interaction. Very rich family of transition curves was observed and presented in the form of phase diagrams. The phenomenon of cooperative trapping of metastable Ising-like spin states was deeply discussed and detailed analytical conditions for its existence are provided. The model was also employed to interpret some well-known experimental results. Copyright EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg 2013