QUALITATIVE DESCRIPTION OF THE TRANSFORMATION OF THERMAL MAGNETO-STRUCTURAL TRANSITIONS IN A CHAIN OF EXCHANGE CLUSTERS UNDER THE EFFECT OF EXTERNAL PRESSURE
V. A. Morozov1,2
1International Tomography Center, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
2Novosibirsk State University, Novosibirsk, Russia
Keywords: molecular magnetics, exchange cluster, spin-crossover, magneto-structural transitions, effective magnetic moment
Abstract
It is shown that in a model chain of exchange clusters magneto-structural transitions are very sensitive to the variation of initial exchange integrals of the model. The cases of three-spin chains (a model of polymer chains of exchange clusters of the family of compounds of “breathing crystal” with the “head-head” motif) and two-spin chains (a model of these chains with the “head-tail” motif) are studied theoretically. A change in the exchange integrals under the effect of external pressure can substantially modify the thermal dependence of the magneto-structural and magneto-resonance properties of “breathing crystals”, which calls for the experimental studies in this aspect. The dependence of these properties on external pressure in “breathing crystals” is expected to have a more complex and diverse form than the ordinary high-temperature shift in the traditional spin-crossover compounds based on iron complexes. Some competing physical factors able to cause such a diversity are described qualitatively. Model calculations show that apart from the temperature shift, the application of external pressure to the “breathing crystals” can result in a change in the low-temperature limit of the effective magnetic moment in the exchange clusters of these compounds.
|
