Unraveling the Environment Influence in Bistable Spin-Crossover Particles Using Magnetometric and Calorimetric First-Order Reverse Curves

A first-order reversal curve (FORC) method is used here to analyze the unexpected change of memory characteristic of spin-crossover microparticles embedded in glass-forming or semicrystalline matrices, reflected in the larger hysteresis loop compared to the bulk. The huge reversibility shown by the reversal curves was attributed to the effect of the matrix, implying a variable external pressure and a cutoff–switch on mechanism of particle–matrix interactions. The FORC analysis indicates that heating and cooling processes in the case of matrix-embedded spin-crossover systems are driven by different mechanisms. In complement of standard magnetometry measurements, a calorimetry method, which demands an alternative method to extract FORC distributions, is introduced for tracking the signature of the composite transformation to understand and control the role of embedding matrices.