Phase transitions of a mixed spin ferrimagnet in high temperatures

Intesar A Obaid; Shakir D Al-Saeedi; Hadey K Mohamad

doi:10.37022/tjmdr.v3i2.450

Intesar A. Obaid Department of Physics, College of Science, University of Thi-Qar, Nassiriya 640001, Iraq
Shakir D. Al-Saeedi Department of Physics, College of Science, University of Thi-Qar, Nassiriya 640001, Iraq
Hadey K. Mohamad College of Science, Al Muthanna University, Samawah550, Iraq

DOI https://doi.org/10.37022/tjmdr.v3i2.450

Abstract

In this research paper molecular mean-field theory (MMFT) has been investigated based on Gibbs-Bogoliubov free energy function of a ferrimagnetics mixed spin-3 and spin-5/2 Blume-Capel model with different magnetic crystal fields. The free energy of the proposed ferrimagnet has been evaluated depending on the trial Hamiltonian operator. Minimizing the free energy, one may induce characteristic features of the longitudinal magnetizations, phase transitions and spin compensation temperatures, in the ranges of low temperatures, respectively. In particular, we study the effect of crystal field domains on the critical phenomena for the proposed model. The sublattice magnetization dependence of free energy function has been discussed as well. Our results predict the existence of multiple spin compensation sites in the disordered Blume-Capel Ising system for a simple cubic lattice.

Keywords: Molecular mean field theory, Ferrimagnetic phase transition, Crystal field domain, Spin free energy function, Curie temperature

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