Blume-Emery-Griffiths Model in a Random Transverse Field
  The effect of the random quantum transverse field $\Omega$ on the tricritical behavior of the spin-1 Blume- Emery- Griffiths (BEG) model is studied using effective field theory. It is found, that the tricritical behavior depends on both the biquadratic interaction $K$, single- ion anisotropy $\Delta$, and the concentration $p$ of the disorder of $\Omega$. Indeed, there exist a special value $p_{1}$ of the probability $p$ below which the tricritical behavior disappears. 
H. Ez-Zahraouy, H. Mahboub, A.Benyoussef, M. J. Ouazzani