中国物理B ›› 2013, Vol. 22 ›› Issue (10): 100508-100508.doi: 10.1088/1674-1056/22/10/100508

• GENERAL • 上一篇    下一篇

Phase diagrams of spin-3/2 Ising model in the presence of random crystal field within the effective field theory based on two approximations

Ali Yigita, Erhan Albayrakb   

  1. a Department of Physics, Çankiri Karatekin University, 18100, Çankiri, Turkey;
    b Department of Physics, Erciyes University, 38039, Kayseri, Turkey
  • 收稿日期:2013-03-26 修回日期:2013-04-16 出版日期:2013-08-30 发布日期:2013-08-30

Phase diagrams of spin-3/2 Ising model in the presence of random crystal field within the effective field theory based on two approximations

Ali Yigita, Erhan Albayrakb   

  1. a Department of Physics, Çankiri Karatekin University, 18100, Çankiri, Turkey;
    b Department of Physics, Erciyes University, 38039, Kayseri, Turkey
  • Received:2013-03-26 Revised:2013-04-16 Online:2013-08-30 Published:2013-08-30
  • Contact: Ali Yigit E-mail:ayigit80@karatekin.edu.tr

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摘要： The bimodal random crystal field (Δ) effects are investigated on the phase diagrams of spin-3/2 Ising model by using the effective-field theory with correlations based on two approximations: the general van der Waerden identity and the approximated van der Waerden identity. In our approach, the crystal field is either turned on or turned off randomly for a given probability p or q=1-p, respectively. Then the phase diagrams are constructed on the (Δ, kT/J) and (p, kT/J) planes for given p and Δ, respectively, when the coordination number is z=3. Furthermore, the effect of randomization of the crystal field is illustrated on the (Δ, kT/J) plane for p=0.5 when z=3, 4, and 6. All these are carried out for both approximations and then the results are compared to point out the differences. In addition to the lines of second-order phase transitions, the model also exhibits first-order phase transitions and the lines of which terminate at the isolated critical points for high p values.

关键词: spin-3/2, random crystal field, effective-field theory, isolated critical point

Abstract: The bimodal random crystal field (Δ) effects are investigated on the phase diagrams of spin-3/2 Ising model by using the effective-field theory with correlations based on two approximations: the general van der Waerden identity and the approximated van der Waerden identity. In our approach, the crystal field is either turned on or turned off randomly for a given probability p or q=1-p, respectively. Then the phase diagrams are constructed on the (Δ, kT/J) and (p, kT/J) planes for given p and Δ, respectively, when the coordination number is z=3. Furthermore, the effect of randomization of the crystal field is illustrated on the (Δ, kT/J) plane for p=0.5 when z=3, 4, and 6. All these are carried out for both approximations and then the results are compared to point out the differences. In addition to the lines of second-order phase transitions, the model also exhibits first-order phase transitions and the lines of which terminate at the isolated critical points for high p values.

Key words: spin-3/2, random crystal field, effective-field theory, isolated critical point

中图分类号:  (Lattice theory and statistics)

  • 05.50.+q
05.70.Fh (Phase transitions: general studies) 64.60.Cn (Order-disorder transformations) 75.10.Hk (Classical spin models)