The quantum transverse spin-2 Ising model with a bimodal random-field in the pair approximation |
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| Institution: | 1. Department of Physics and Center for Theoretical Physics, Seoul National University, Seoul 151-747, Republic of Korea;2. Institut Jean Lamour, Groupe de Physique Statistique, Département de Physique de la Matière et des Matériaux, CNRS-UMR 7198, Vandoeuvre-lès-Nancy, F-54506, France;1. Department of Mechanical and Manufacturing Engineering, Engineering Faculty, Bilecik S.E. University, Bilecik, Turkey;2. Department of Chemistry, Faculty of Arts and Sciences, Eskisehir Osmangazi University, Eskisehir, Turkey;1. Instituto Federal de Educação, Ciência e Tecnologia de Mato Grosso – IFMT, Campus Cuiabá, Rua Professora Zulmira Canavarros, 93, 78005-200 Cuiabá, MT, Brazil;2. Instituto de Física, Universidade Federal de Mato Grosso – UFMT, Av. Fernando Corrêa da Costa, 2367, Bloco F, Sala 209, 78060-900 Cuiabá, MT, Brazil;3. Department of Physics and Astronomy, The University of Georgia – UGA, 30602-2451 Athens, GA, USA;1. Çank?r? Karatekin University, Department of Physics, 18100, Çank?r?, Turkey;2. Erciyes University, Department of Physics, 38039, Kayseri, Turkey |
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| Abstract: | In this paper, we have investigated the bimodal random-field spin-2 Ising system in a transverse field by combining the pair approximation with the discretized path-integral representation. The exact equations for the second-order phase transition lines and tricritical points are obtained in terms of the random field H, the transverse field G and the coordination number z. It is found that there are some critical values for H and G where the tricritical points disappear for given z. We have also observed that the system presents reentrant behavior which may be caused by the quantum effects and randomness. The phase diagram with respect to the random field and the second-order phase transition temperature are studied extensively for given values of the transverse field and the coordination number. |
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