Second- to first-order transition in two coupled antiferromagnetic rings

Physics of Condensed Matter (Impact Factor: 1.28). 05/2006; 51(4):473-476. DOI:10.1140/epjb/e2006-00255-1

ABSTRACT We numerically investigate an S=1/2 spin model, in which two
dimerized antiferromagnetic rings interact with each other
ferromagnetically. It is shown that the order of the magnetoelastic
transition is strongly affected by the interring coupling J⊥ and
there may exist a critical J⊥* dividing the first-order
transition and the continuous transition.

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    ABSTRACT: We examine the dynamic phase transitions and the dynamic compensation temperatures, within a mean-field approach, in the mixed spin-3/2 and spin-5/2 Ising system with a crystal-field interaction under a time-varying magnetic field on a hexagonal lattice by using Glauber-type stochastic dynamics. The model system consists of two interpenetrating sublattices with σ=3/2 and S=5/2. The Hamiltonian model includes intersublattice, intrasublattice, and crystal-field interactions. The intersublattice interaction is considered antiferromagnetic and to be a simple but interesting model of a ferrimagnetic system. We employ the Glauber transition rates to construct the mean-field dynamic equations, and we solve these equations in order to find the phases in the system. We also investigate the thermal behavior of the dynamic sublattice magnetizations and the dynamic total magnetization to obtain the dynamic phase transition points and compensation temperatures as well as to characterize the nature (continuous and discontinuous) of transitions. We also calculate the dynamic phase diagrams including the compensation temperatures in five different planes. According to the values of Hamiltonian parameters, five different fundamental phases, three different mixed phases, and six different types of compensation behaviors in the Néel classification nomenclature exist in the system. KeywordsMixed-spin Ising system-Dynamic phase transitions-Dynamic compensation temperature-Dynamic phase diagrams-Glauber-type stochastic dynamics
    Journal of Statistical Physics 140(5):934-947. · 1.40 Impact Factor

P. F. Li