Title: Phase diagrams and critical behaviours of the mixed spin-5/2 and spin-7/2 Ising system
Author(s):

	M. Karimou (Ecole Nationale Supérieure de Génie Energétique et Procédés (ENSGEP), University of Abomey, Republic of Benin; Institute of Mathematics and Physical Sciences (IMSP), Republic of Benin) ,
	R.A. Yessoufou (Institute of Mathematics and Physical Sciences (IMSP), Republic of Benin; University of Abomey-Calavi, Department of Physics, Republic of Benin) ,
	G. Dimitri Ngantso (GSMC, Faculty of Sciences and Techniques, Marien Ngouabi University, Brazzaville, Congo and LMPHE, Faculty of Sciences Mohammed V University, Rabat, Morocco) ,
	F. Hontinfinde (Institute of Mathematics and Physical Sciences (IMSP), Republic of Benin; University of Abomey-Calavi, Department of Physics, Republic of Benin) ,
	E. Albayrak (Erciyes University, Department of Physics, 38039, Kayseri, Turkey)

We used mean-field theory based on the Bogoliubov inequality for the Gibbs free energy to examine the magnetic properties of a mixed spin-5/2 and spin-7/2 Blume-Capel ferrimagnetic system. The thermal behaviours of the system magnetization are classified according to the extended Néel nomenclature. The system exhibits compensation phenomena where a complete cancellation of sublattice magnetizations is observed below the critical temperature. Temperature-dependent phase diagrams are constructed for the case of unequal sublattice crystal field interactions. Under appropriate conditions, our calculations reveal first-order transitions in addition to second-order ones previously observed in Monte Carlo simulations.

Key words: mean-field theory, mixed-spin system, magnetization, compensation temperature, phase transitions
PACS: 61.10.Nz, 61.66.Fn, 75.40.Gb

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