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arXiv · 2012.01948

Ferromagnetic and spin-glass like transition in the $q$-neighbor Ising model on random graphs

A. Krawiecki
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Abstract

The $q$-neighbor Ising model is investigated on homogeneous random graphs with a fraction of edges associated randomly with antiferromagnetic exchange integrals and the remaining edges with ferromagnetic ones. It is a nonequilibrium model for the opinion formation in which the agents, represented by two-state spins, change their opinions according to a Metropolis-like algorithm taking into account interactions with only a randomly chosen subset of their $q$ neighbors. Depending on the model parameters in Monte Carlo simulations phase diagrams are observed with first-order ferromagmetic transition, both first- and second-order ferromagnetic transitions and second-order ferromagnetic and spin-glass-like transitions as the temperature and fraction of antiferromagnetic exchange integrals are varied; in the latter case the obtained phase diagrams qualitatively resemble those for the dilute spin-glass model. Homogeneous mean-field and pair approximations are extented to take into account the effect of the antiferromagnetic exchange interactions on the ferromagnetic phase transition in the model. For a broad range of parameters critical temperatures for the first- or second-order ferromagnetic transition predicted by the homogeneous pair approximation show quantitative agreement with those obtained from Monte Carlo simulations; significant differences occur mainly in the vicinity of the tricritical point in which the critical lines for the second-order ferromagnetic and spin-glass-like transitions meet.

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BibTeXRIS

A. Krawiecki. 2020-12-03. Ferromagnetic and spin-glass like transition in the $q$-neighbor Ising model on random graphs. https://doi.org/10.1140/epjb/e2020-10288-9

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