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العنوان
Magnetothermal Properties and Magnetocaloric Effect in some 𝑹𝑭𝒆𝟐 Compounds /
المؤلف
Afify, Rana Hesham Gamal El-Din.
هيئة الاعداد
باحث / رنا هشام جمال الدين عفيفي
مشرف / أحمد عبد الغني عوض
مشرف / منى عبد العزيز حسين
مشرف / محمد شريف يحيى
تاريخ النشر
2021.
عدد الصفحات
96 p. :
اللغة
الإنجليزية
الدرجة
ماجستير
التخصص
الفيزياء والفلك (المتنوعة)
تاريخ الإجازة
1/1/2021
مكان الإجازة
جامعة عين شمس - كلية العلوم - الفيزياء
الفهرس
Only 14 pages are availabe for public view

from 96

from 96

Abstract

Temperature dependence of magnetization shows that ErFe_2 is ferrimagnetic with compensation point around 471 K and Curie temperature close to 591 K. Applying magnetic field on ErFe_2 induces canting in moments of Er sublattice. We calculated the canting angles at 0.64 T_comp at which they have the same magnetic state. The Fe-Er interaction plays the biggest role in increasing the magnetic and consequently the total entropy by increasing the magnetic field. Using the values of bulk and shear moduli, we calculated θ_D which equals 258.24 K. Using the calculated DOS at E_F , the electronic heat capacity coefficient γ_e was found to be 27 mJ⁄mole.K^2.
For an applied magnetic field change up to 6 T, we found that the highest value of the direct magnetocaloric potential near Curie temperature is around 0.23 J/mole.K, while the highest value of the inverse magnetocaloric potential near compensation temperature is around 0.13 J/mole.K. We predict that any compound without compensation temperature like DyFe_2 has no an inverse MCE. The adiabatic temperature change increases by around 0.5 k/T and the maximum value reaches 3 K, for an applied magnetic field change up to 6 T.
The two-sublattice molecular field model succeeded to explain the thermomagnetic properties for ErFe_2.