Eur. Phys. J. B 15, 317-326 (2000)
https://doi.org/10.1007/s100510051131

One-dimensional Ising-like systems: an analytical investigation of the static and dynamic properties, applied to spin-crossover relaxation^*

¹ Laboratoire de Magnétisme et d'Optique, CNRS-Université de Versailles/St. Quentin en Yvelines, 45 avenue des États Unis, 78035 Versailles Cedex, France
² Institut für Anorganische Chemie und Analytische Chemie der Johannes Gutenberg-Universität Mainz, 55090 Mainz, Germany

Received: 29 October 1999
Revised: 30 December 1999
Published online: 15 May 2000

Abstract

We investigate the dynamical properties of the 1-D Ising-like Hamiltonian taking into account short and long range interactions, in order to predict the static and dynamic behavior of spin crossover systems. The stochastic treatment is carried out within the frame of the local equilibrium method [1]. The calculations yield, at thermodynamic equilibrium, the exact analytic expression previously obtained by the transfer matrix technique [2]. We mainly discuss the shape of the relaxation curves: (i) for large (positive) values of the short range interaction parameter, a saturation of the relaxation curves is observed, reminiscent of the behavior of the width of the static hysteresis loop [3]; (ii) a sigmoidal (self-accelerated) behavior is obtained for large enough interactions of any type; (iii) the relaxation curves exhibit a sizeable tail (with respect to the mean-field curves) which is clearly associated with the transient onset of first-neighbor correlations in the system, due to the effect of short-range interactions. The case of negative short-range interaction is briefly discussed in terms of two-step properties.