The spin-1 Ising model on a two-layer Bethe lattice with FM/AFM interactions


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ALBAYRAK E. , Akkaya S., Cengiz T.

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, cilt.321, ss.108-116, 2009 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 321 Konu: 2
  • Basım Tarihi: 2009
  • Doi Numarası: 10.1016/j.jmmm.2008.08.084
  • Dergi Adı: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
  • Sayfa Sayıları: ss.108-116

Özet

Two-layer Bethe lattice with the Ising spins of the top layer having only ferromagnetic (FM) interactions and the bottom layer having only antiferromagnetic (AFM) interactions are allowed to interact with the interlayer interaction of either FM or AFM type. The model is studied by using the exact recursion relations in a pairwise approach for given coordination numbers q = 3, 4 and 6 with equal external magnetic fields acting on the layers. The phase diagrams of the model are obtained on different planes for given system parameters by studying the ground state (GS) phase diagrams and the thermal variations of the order-parameters and the response functions, i.e. the susceptibility and the specific heat, in detail. The model presents second-and first-order phase transitions, and where their lines are combined is the tricritical point. The critical end points also exist. The reentrant behavior is also seen when the model presents two Neel temperatures. (C) 2008 Elsevier B.V. All rights reserved.