Effects of the random single-ion anisotropy and random magnetic field in the spin-3/2 Blume-Capel model

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:422

Article

da Silva, W. P.¹  de Arruda, P. H. Z.¹  Tunes, T. M.²  Godoy, M.^1,3  de Arruda, A. S.¹ 

[1] Univ Fed Mato Grosso, Inst Fis, BR-78060900 Cuiaba, Mato Grosso, Brazil

[2] Univ Fed Mato Grosso, Inst Engn, BR-78060900 Varzea Grande, Mato Grosso, Brazil

[3] Univ Antwerp, Dept Fys, Groenenborgerlaan 171, B-2020 Antwerp, Belgium

关键词: Blume Capel model;    Random fields;    Mean-field approximation;   

DOI  :  10.1016/j.jmmm.2016.08.094

来源: Elsevier

【 摘 要 】

We have studied the effects of the random single-ion anisotropy and random magnetic field in the phase diagram and in the thermodynamic properties of the spin -3/2 Blume-Capel model via Curie-Weiss mean-field approximation. The phase diagrams were built in the planes temperature versus single-ion anisotropy, temperature versus magnetic field, temperature versus random parameters and the dependencies of magnetization were plotted versus temperature and single-ion anisotropy. These diagrams show that, in the space (D/J - T/J), the type (first-or second-order) of the phase transition between the ferromagnetic and paramagnetic phases is dependent on the random parameters. Therefore, within these conditions the model presents tricritical behavior. For large values, and a certain critical value of the random parameters, the phase transition is only of second-order, but it is of first-order within the ordered phase, between the phase with m = 1/2 and m = 3/2, which ends in a terminal critical point. (C) 2016 Elsevier B.V. All rights reserved.

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