The critical behaviors and the phase diagram of the mixed spin-1/2 and spin-2 Ising system on the Bethe lattice


Albayrak E. , Yigit A.

PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, cilt.242, ss.1510-1521, 2005 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 242 Konu: 7
  • Basım Tarihi: 2005
  • Doi Numarası: 10.1002/pssb.200440029
  • Dergi Adı: PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
  • Sayfa Sayıları: ss.1510-1521

Özet

yThe thermal behaviors of the order-parameters and the phase diagram for the coordination numbers with q = 3, 4, 5 and 6 for the mixed spin-1/2 and spin-2 Blume-Capel Ising ferrimagnetic system (J < 0) for the nearest-neighbor interactions is studied on the Bethe lattice by using the exact recursion equations. All the functions of interest, the sublattice magnetizations, quadrupolar-order parameter, free energy etc., are obtained in terms of these recursion relations. The second- and first-order phase transition lines, therefore the existence of the tricritical points are investigated in detail by studying the thermal variations of the sublattice magnetizations and the free energy and it was found that the system presents tricritical points for q >= 5, which means that the nonexistence of the triciritcal point for q = 4 is in agreement with the result of a Monte Carlo simulation and in disagreement with the result of an effective field theory. It should also be mentioned that the system presents two compensation temperatures for q >= 4, therefore, the lines of the compensation temperatures are also shown in the phase diagrams.