Phase diagram of the spin-1 XXZ Heisenberg ferromagnet with a single-ion anisotropy

Strecka, Jozef; Dely, Jan; Canova, Lucia

Phase diagram of the spin-1 XXZ Heisenberg ferromagnet with a single-ion anisotropy

Authors

Strecka, Jozef

Dely, Jan

Canova, Lucia

Description

Phase diagram of the spin-1 quantum Heisenberg model with both exchange as well as single-ion anisotropy is constructed within the framework of pair approximation formulated as a variational procedure based on the Gibbs-Bogoliubov inequality. In this form adapted variational approach is used to obtain the results equivalent with the Oguchi's pair approximation. It is shown that the single-ion anisotropy induces a tricritical behaviour in the considered model system and a location of tricritical points is found in dependence on the exchange anisotropy strength.
12 pages, 3 figures, preprint submitted to Chin. J. Phys