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دراسة الخواص المغناطيسية لنظام فيريمغناطيسي ذي برم مختلط باستخدام تقريب متوسط المجال == Study of the Magnetic Properties of a Mixed Spin Ferrimagnetic System by Using Mean Field Approximation
اسم المؤلف:
اسماء مزعل جاسم
اسم المشرف:
حسن عبد ياسر | هادي قاسم محمد
الموضوع العام:
علوم الفيزياء
السنة:
2017
الموضوع الدقيق:
الفيزياء
الدرجة:
ماجستير
الجامعة:
جامعة ذي قار - كلية العلوم - قسم الفيزياء
اللغة:
العربية
مكان الجامعة:
ذي قار
الصفحات الاولى:
📎 26T1607 - p.pdf
المستخلص:
In this research it has been investigated the magnetic properties of a mixed spin - 2 and spin - 7/2 lsing binary ferrimagnetic system which is numerically solved by using the mean - field approximation (MFA), for a square lattice and simple cubic one; respectively.The magneto crystalline anisotropies have carefully been changed so as to investigate an interesting phenomenon which is called “Compensation phenomenon” where it has been found that the mixedspin Ising system which is considered has one compensation temperature and ) 4z ( square for a 85 . 2 1 . 3 B D , 85 . 1 1 . 2 B D when the considered system , respectively. Whereas lattice ) 6z ( simple cubic A atoms of for the sublattice anisotropies compensation points multi has in the range 7.1 DA 6.1, 10.4 DA 9.2 for a square and simple cubic lattice, respectively. Besides that it has been studied this phenomenon in the presence of an external magnetic field. We have , 1 . 0 2 . 0 H , , i.e. H lues of t a certain range of negative va found tha gives rise to the multi compensation points. On the other hand, the obtained results indicate that the considered system has experienced first - order and second - order phase transitions, in the planes mA,T , mB ,T respectively. At certain values of sublattices observe that the ordered , one can H , in the absence of A D anisotropies may show the first order phase transition rom the phases at T 0K SA 2 state to the SB 7 / 2 state, when the value of anisotropyDB decreases.As well, we have examined the phase transitions within the calculation of the free energy function on the basis of Bogoliubov inequality in the plane f ,T to obtain precisely results compared of both crystalline for ) TM, ( se ones have been shown in the plane tho sublattices. Our results are encouraged and helpful to support and clarify the characteristic features in a series bimetallic molecularbased magnets. Besides that these magnetic materials have applications in the area of thermo - magneto recording.
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