The quantum transverse spin-2 Ising model with a bimodal random-field in the pair approximation

Canko O., Albayrak E., Keskin M.

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, vol.294, no.1, pp.63-71, 2005 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 294 Issue: 1
  • Publication Date: 2005
  • Doi Number: 10.1016/j.jmmm.2004.11.579
  • Journal Name: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.63-71
  • Keywords: discretized path integral representation, bimodal random field, transverse field effects, TRICRITICAL POINTS, BETHE LATTICE, PHASE-DIAGRAM, SYSTEMS, FERROMAGNET
  • Erciyes University Affiliated: Yes

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. (c) 2004 Elsevier B.V. All rights reserved.