"

Cookies ussage consent

Our site saves small pieces of text information (cookies) on your device in order to deliver better content and for statistical purposes. You can disable the usage of cookies by changing the settings of your browser. By browsing our site without changing the browser settings you grant us permission to store that information on your device.

I agree, do not show this message again.

Study of the random crystal field effect on spin-1 and spin-3/2 Blume-Capel models by the position space renormalization group theory

M. EL BOUZIANI1,* , A. GAYE1

Affiliation

  1. Laboratoire L.P.M.C., Equipe de Physique Théorique, Département de Physique, Faculté des Sciences, Université Chouaib Doukkali, B.P. 20, 24000 El Jadida, Maroc.

Abstract

We study the impact of a random crystal field on magnetic materials of spin-1 and spin-3/2, described by the Blume-Capel model. For this purpose, we use a real space renormalization group approximation, namely the Migdal-Kadanoff one. We give the principal fixed points and phase diagrams found, what allows us to have a better understanding of the critical behavior in these materials. In the two-dimensional case, we observe that randomness, even in small amounts, removes totally the first order phase transitions, replacing them by a smooth continuation and this result is common to spin-1 and spin-3/2 materials; there is only the appearance of second order transitions between the ordered and disordered phases. But at three-dimensions, there is a clear difference between the critical behaviors of spin-1 and spin-3/2 materials. Indeed, for the spin-1 three-dimensional materials, the first order transition is removed, whatever the amount of randomness introduced. On the other hand, for the three-dimensional spin-3/2 materials, the first order transition resists to small amounts of randomness and the first order transition line finishes inside the ordered phase by an end-point. As the randomness increases, the first order transition line becomes shorter and above a certain threshold, defined by a critical value of probability, it disappears completely and is converted into smooth continuation between the ferromagnetic phases..

Keywords

Blume-Capel, Random crystal field, First order transition, Second order transition, Renormalization group.

Submitted at: Sept. 28, 2013
Accepted at: Nov. 7, 2013

Citation

M. EL BOUZIANI, A. GAYE, Study of the random crystal field effect on spin-1 and spin-3/2 Blume-Capel models by the position space renormalization group theory, Journal of Optoelectronics and Advanced Materials Vol. 15, Iss. 11-12, pp. 1233-1238 (2013)