The most general spin-3/2 Ising model with up-down symmetry is investigated on a honeycomb lattice. The partition function on a surface in the space spanned by the coupling constants J, K, L, and M was found exactly. The explicit expression for the quadrupolar order parameter with the inclusion of an external crystal field of strength Δ is obtained. It is shown that this order parameter exhibits in general a simple power-law dependence on T-${\mathit{T}}_{\mathit{c}}$ near ${\mathit{T}}_{\mathit{c}}$.

• Received 18 May 1994

DOI:https://doi.org/10.1103/PhysRevB.50.6829