The FM/AFM bilayer Bethe lattice with FM or AFM interlayer interactions


Albayrak E.

PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, cilt.246, ss.226-236, 2009 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 246 Konu: 1
  • Basım Tarihi: 2009
  • Doi Numarası: 10.1002/pssb.200844204
  • Dergi Adı: PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
  • Sayfa Sayıları: ss.226-236

Özet

The bilayer Bethe lattice with the Ising spins of the top layer having only ferromagnetic (FM) interactions and the spins of the bottom one having only antiferromagnetic (AFM) interactions were allowed to interact via the interlayers interaction either FM of AFM type. The problem was analyzed 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 models were 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 with five distinct GS configurations presents only the second-order phase transition lines, i.e. the lines of the Neel temperatures T(N). Two T(N)'s were obtained for q=6 in the transition regions from the AFM phases to the FM phases at low temperatures, as a result the T(N) lines show reentrant behavior for q=6. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim