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

Jozef Strecka·Jan Dely·Lucia Canova
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Abstract

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.

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Jozef Strecka, Jan Dely, Lucia Canova. 2007-09-04. Phase diagram of the spin-1 XXZ Heisenberg ferromagnet with a single-ion anisotropy. https://arxiv.org/abs/cond-mat/0611254

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