Phase diagram and tricritical behavior of the spin-1 Heisenberg model with Dzyaloshinskii-Moriya interactions

Using the two-spin cluster mean-field method, the spin-1 Heisenberg model with Dzyaloshinskii-Moriya (DM) interactions is studied for the simple cubic lattice. For the case of the DM vector coupling (D) over right arrow = D (z) over cap (D is the DM interaction parameter and z is the unit vector of the z-axis direction), the phase diagram of this system and the thermal behavior of the magnetization are obtained, and it is found that the system exhibits the tricritical point. The critical behavior of the system may be interpreted as a result of a competition between the exchange interaction and the DM interaction. (c) 2006 Elsevier B.V. All rights reserved.