https://doi.org/10.1140/epjb/e2011-10825-7
Numerical study of the mixed spin-1 and spin-5/2 BEG model on the Bethe lattice
1
Département de Physique (FAST) et
Institut des Mathématiques et de Sciences Physiques (IMSP), Université d'Abomey-Calavi, 01, BP 613, Porto-Novo, Benin
2
Laboratoire de Physique Théorique, Département de Physique, Université Abou Bakr Belkaid, Tlemcen, Algérie
3
The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy
Corresponding author: a fhontinfinde@yahoo.fr
Received:
27
October
2010
Revised:
9
March
2011
Published online:
4
May
2011
The mixed spin-1 and spin- ferromagnetic Ising model with bilinear (J) and biquadratic (K) nearest-neighbor exchange interactions and a single-ion potential or crystal-field interaction (D) is studied on
the Bethe lattice by means of exact recursion equations. First,
the phase diagram of the system at zero temperature is obtained in the (D/Jq, K/Jq) plane, where q denotes the coordination number of the lattice. Second,
the sublattice magnetizations
as functions of the temperature, the crystal-field and the biquadratic
interaction strengths are thoroughly investigated. For q=3,
the resulting phase diagrams show first and second order
phase transitions as well as compensation points where the net
magnetization of the whole lattice
should vanish in the antiferromagnetic version of the model.
One interesting feature of the model concerns the presence of tricritical points.
Our calculations show that at non-zero temperature, none of the sublattice can order separately. However, under an external magnetic
field, some interesting phase diagrams with partially ordered phases arise.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2011