Hysteretic behavior of Fe(phen)2(NCS)2 spin-transition microparticles vs. the environment: A huge reversible component resolved by first order reversal curves

We discuss the influence of the embedding matrix on the thermal hysteretic behavior of spin transition microparticles of Fe(phen)2(NCS)2 by using a series of experimental first order reversal curves (FORCs). The shape of FORCs supports the hypothesis considering additional interactions between the spin-transition microparticles and the embedding matrix, which compares to a negative pressure on the particles. A mean-field approach based on negative variable external pressures, together with a cut off/switch on of particles-matrix interactions accounts for the experimental features.