Gaussian Fluctuations of Two Molecular Fields in the Blume-Emery-Griffits Model
W. Jaworski1 , Z. Jacyna-Onyszkiewicz1
1 Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland
Acta Physica Polonica A, 119, 846-849 (2011)
The Blume-Emery-Griffiths model for spins S=1 in a bilayer with z=5 nearest neighbours is studied with the use of Gaussian fluctuations approximation. The fluctuations of two molecular fields, connected with two order parameters, are introduced. Their influence on phase diagrams for non-negative values of the biquadratic coupling constant is taken under consideration. The results are compared with those obtained by the mean-field approximation and discussed.