The temperature induced transition in one-dimensional bistable molecular magnetic systems with degenerate states is discussed. This phenomenon derives from the existence of two stable spin configurations in transition metallic ion, separated by an energy gap, that determines a certain spin state. A new microscopic model is proposed in order to account for the variation of molecular size in observed magnetic states. The behavior of 1D bistable molecular chain considering both structural and magnetic properties have been studied in framework of simple conception in which the molecules are strongly fixed on chain’s sites and are connected by springs.
The stochastic kinetics of a photoinduced phase transition in spin-crossover compounds in the presence of environmental background and systems internal noises were studied. The correlation phenomena that determine the color of internal and external noises was taken into account. The mathematical framework for the study of light-induced transition in spin-crossover nanoparticles was based on the Langevin equation and steady solution of corresponding Fokker-Planck equation. The system behavior was described by nonequilibrium (dynamic) potential in terms of Lyapunov functions for the deterministic case and by stochastic Fokker-Planck potential in the noise case action.
We investigate the light induced optical hysteresis of spin-crossover compound driven by Gaussian noise. The stationary states was found from dynamic potential of noiseless system described in terms of Lyapunov functions. Cooperativity causes bistability of the steady state and provokes light-induced thermal and optical hysteresis. We study the influence of noise action on cooperative effects of photoexcited spin-crossover compound, leading to changes of system hysteresis. The stochastic dynamics of spin-crossover system was described following the Langevin formalism for noise driven system.
In this work the macroscopic phenomenological model of spin-crossover compounds in term of relaxation rate in mean
field approach have been comprehensive analyzed. It is given the more accurate description of spin-crossover model,
which take into consideration environmental noise influence modeled as interaction with a heath bath. Also we have
obtained the distribution of probability density function for different values of multiplicative and additive noise intensity.
The correlation between the noises is considered. The calculations of mean first passage time of metastable state for
correlated case have been performed.