Condensed Matter Physics, 2009, vol. 12, No. 2, pp. 167181
DOI:10.5488/CMP.12.2.167
Title:
Spin3/2 Ising model on a twolayer Bethe lattice with FM/AFM interactions
Author(s):

E. Albayrak
(Erciyes University, Department of Physics, 38039, Kayseri, Turkey)
,


A. Yigit
(Erciyes University, Department of Physics, 38039, Kayseri, Turkey)

Twolayer Bethe lattice whose lattice sites are occupied with spin3/2 atoms is solved exactly by using the 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 ferromagnetic (FM) and antiferromagnetic (AFM) interactions for the spins of the upper and lower layers, respectively, and either FM or AFM type interactions between the adjacent spins of the layers are assumed. The phase diagrams of the model are studied on different planes for given system parameters by obtaining 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. It was found that the model presents both second and firstorder phase transitions. The reentrant behavior is seen when the model presents two Néel temperatures for higher q values. The existence of the tricritical point and critical end points is also confirmed.
Key words:
Bethe lattice, spin, ground state, fm/afm, layer, phase
PACS:
05.50.+q, 68.35.Rh, 64.60.Cn
Comments: Figs. 4, Refs. 28, Tabs. 1
