J. Phys. I France
Volume 3, Numéro 6, June 1993
Page(s) 1463 - 1473
DOI: 10.1051/jp1:1993191
J. Phys. I France 3 (1993) 1463-1473

Ising-like model for the two step spin-crossover of binuclear molecules

A. Bousseksou1, 2, F. Varret1 and J. Nasser1

1  Département de Recherches Physiques UA CNRS n° 71, Université Pierre et Marie Curie, 75252 Paris Cedex 05, France
2  Laboratoire de Chimie de Coordination du CNRS, 205 route de Narbonne, 31077 Toulouse Cedex, France

(Received 29 July 1992, revised 3 December 1993, accepted 18 February 1993)

We present a two-sublattice Ising-type model, involving one intramolecular interaction treated rigorously and intermolecular interactions treated in the mean-field approach, in order to describe the two-step transition exhibited by a bi-nuclear spin-crossover complex. Spontaneous symmetry breakings can be obtained according to the relative values of the interactions parameters. The phase diagram is given and the experimental data of [ Fe(bt) (NCS) 2] 2bpym are treated in the present model.

31.30N - 75.90

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