Effect of the short-range interaction on critical phenomena in elastic interaction systems

Abstract

The elastic interaction, induced by the lattice distortion due to the difference of the molecular size, causes an effective long-range interaction. In spin-crossover (SC) compounds, local bistable states, i.e., high-spin and low-spin states have different molecular sizes, and the elastic interaction is important. In bipartite lattices, e.g., the square lattice, the ground state can be two types of phases: ferromagnetic-like (FM) and antiferromagnetic-like (AFM) phases. In systems like SC compounds, the former phase consists of all small or large molecules, and the latter phase has the configuration of alternating small and large molecules. In fact, both cases are observed in SC systems. In this paper, we have studied the effect of the short-range interaction in the elastic system on the properties of those order-disorder phase transitions. We have obtained a phase diagram in the coordinates of the temperature and the strength of the short-range interaction, including the metastable structures. We show that effects of the short-range interaction are essentially different for FM and AFM phase transitions. In the FM transition, the long-range interaction of elasticity is relevant, and the system exhibits a phase transition in the mean-filed universality class. In this case, the long-range interaction strongly enhances the FM order, and it works cooperatively with the short-range interaction. In contrast, in the AFM transition, the elastic interaction slightly enhances the AFM order, but essentially it does not contribute to the ordering, and the system shows a transition in the Ising universality class. We have found that in the border region between FM and AFM phases, the AFM phase has an advantage at finite temperatures. We discuss the critical properties of two-step SC transitions with comparison between the elastic interaction model and conventional SC models (Ising-like models).

32 pages,12 figures

References in corpus (5)

• Simple Two-Dimensional Model for the Elastic Origin of Cooperativity among Spin States of Spin-Crossover Complexes
• Realization of the mean-field universality class in spin-crossover materials
• Monte Carlo simulation of pressure-induced phase transitions in spin-crossover materials
• Macroscopic nucleation phenomena in continuum media with long-range interactions
• Critical temperature and correlation length of an elastic interaction model for spin-crossover materials

Cited by in corpus (12)

• Spin-state ice in geometrically frustrated spin-crossover materials
• Equilibrium, Metastability, and Hysteresis in a Model Spin-crossover Material with Nearest-neighbor Antiferromagnetic-like and Long-range Ferromagnetic-like Interactions
• Termination of the Berezinskii-Kosterlitz-Thouless phase with a new critical universality in spin-crossover systems
• Nontrivial phase diagram for an elastic interaction model of spin crossover materials with antiferromagnetic-like short-range interactions
• Cooperative Phenomena in Spin Crossover Systems
• The Origin of Mean-Field Behavior in an Elastic Ising Model
• Multistability in an unusual phase diagram induced by the competition between antiferromagnetic-like short-range and ferromagnetic-like long-range interactions
• Multiple Coulomb phases with temperature tunable ice rules in pyrochlore spin crossover materials
• Monte Carlo Studies of the Ising Antiferromagnet with a Ferromagnetic Mean-field Term
• Spin-state smectics in spin crossover materials
• Density of states for systems with multiple order parameters: a constrained Wang-Landau method
• Pressure-induced two-step spin crossover in double-layered elastic model