Dynamical Ising-like model for the two-step spin-crossover systems

In order to reproduce the two-step relaxation observed experimentally in spin-crossover systems, we investigate analytically the static and the dynamic properties of a two-sublattice Ising-like Hamiltonian. The formalism is based on a stochastic master equation approach. It is solved in the mean-field approximation, and yields two coupled differential equations that correspond to the HS fractions of the sublattices A and [email protected] ; [email protected]

Physical parameter distribution in spin transition systems derived from FORC data

Spin crossover compounds show a first order phase transition that can be accompanied by a thermal hysteresis. In this paper we present the analogies between this class of substances and magnetic systems with a domain structure. We show the possibilities of study the thermal hysteresis of spin crossover solids using Preisach-type models and of the First Order Reversal Curves (FORC) method. Experimental FORE diagrams were obtained for pure and diluted spin transition system [Fe(x)Zn(1-x)(btr)(2)(NCS)(2)]H(2)O, where x governs, through cooperative interactions, the width of the thermal hysteresis loops. A parametrical identification of the distributions corresponding to inter-domains interactions domain size was performed also using an Ising like model

Thermo- and piezochromic properties of [Fe(hyptrz)]A2· H2O spin crossover 1D coordination polymer: Towards spin crossover based temperature and pressure sensors

We have used reflectance measurements to investigate the effect of a hydrostatic pressure on the molecular 1D spin crossover coordination polymer [Fe(hyptrz)]A2·H2O (hyptrz=4-(3′- hydroxypropyl)-1,2,4-triazole and A=4-chloro-benzenesulfonate) Rev. Sci. Instrum. 80 (2009) 123901. Both thermal and pressure hysteresis have been recorded at different pressures and temperatures, respectively, in order to obtain valuable information about the optimal conditions of their use as wireless temperature and pressure sensors. The experimental analysis has been completed with a theoretical study and potential applications in terms of temperature and pressure wireless detection are discussed. © 2014 Elsevier B.V