scholarly journals Modeling the Magnetocaloric Effect of Nd0.67Ba0.33Mn0.98 Fe0.02O3 by the Mean Field Theory

2020 ◽  
Author(s):  
Mohamed Hsini ◽  
Sadok Zemni
Keyword(s):  
Field Theory ◽  
Phase Transition ◽  
Magnetic Properties ◽  
Magnetic Fields ◽  
Magnetocaloric Effect ◽  
Mean Field Theory ◽  
Mean Field ◽  
Entropy Change ◽  
Magnetization Curves ◽  
The Mean

In this paper, we have exploited the mean field theory combined with the Bean-Rodbell model to justify the magnetocaloric effect (MCE) in Nd0.67Ba0.33Mn0.98Fe0.02O3 sample. The simulation of some magnetic properties has been investigated. Modeling magnetization curves have been successfully achieved using this model. The second-order ferromagnetic-paramagnetic (FM-PM) phase transition of our system has been verified through the value of the parameter which controls the transition nature in the Bean-Rodbell model. Theoretical and experimental expressions, which have rated the magnetic entropy change ( − ∆ S M ) under various magnetic fields, have been derived. Theoretical ( − ∆ S M ) curves have been compared to the experimental ones.

scholarly journals Magnetocaloric Effect in Nanosystems Based on Ferromagnets with Different Curie Temperatures

2021 ◽  
Vol 132 (1) ◽  
pp. 79-93
Author(s):  
M. A. Kuznetsov ◽  
A. B. Drovosekov ◽  
A. A. Fraerman
Keyword(s):  
Field Theory ◽  
Magnetocaloric Effect ◽  
Landau Theory ◽  
Mean Field Theory ◽  
Mean Field ◽  
Maxwell Relation ◽  
Magnetic Cooling ◽  
The Mean ◽  
Curie Temperatures ◽  
Good Agreement

Abstract The magnetocaloric effect in nanosystems based on exchange-coupled ferromagnets with different Curie temperatures is calculated within the mean-field theory. Good agreement between the results of the mean-field theory and the Landau theory, valid near the critical phase transition temperature, is demonstrated for a flat-layered Fe/Gd/Fe structure. We show that a high magnetic cooling efficiency in this system is attainable in principle and prove the validity of the Maxwell relation, enabling an experimental verification of the predictions made. The theory developed for flat-layered structures is generalized to a granular medium.

Modeling the Magnetocaloric Effect of La0.8MnO3 by the Mean-Field Theory

2019 ◽  
Vol 33 (4) ◽  
pp. 1143-1149
Author(s):  
C. Henchiri ◽  
A. Benali ◽  
T. Mnasri ◽  
M. A. Valente ◽  
E. Dhahri
Keyword(s):  
Field Theory ◽  
Magnetocaloric Effect ◽  
Mean Field Theory ◽  
Mean Field ◽  
The Mean

Critical Behavior of Gd5Si2Ge1.9Ga0.1 near the Ferromagnetic-Paramagnetic Phase Transition

2013 ◽  
Vol 873 ◽  
pp. 855-860 ◽  
Author(s):  
Zeng Ru Zhao ◽  
Gao Feng Wang ◽  
Xue Feng Zhang
Keyword(s):  
Phase Transition ◽  
Critical Behavior ◽  
Scaling Law ◽  
Mean Field Theory ◽  
Mean Field ◽  
Entropy Change ◽  
Paramagnetic Phase ◽  
Range Type ◽  
Fisher Model ◽  
The Mean

The critical behavior near the ferromagnetic-paramagnetic phase transition in Gd5Si2Ge1.9Ga0.1 has been investigated using a method based on the field dependence of isothermal entropy change. The reliability of the critical exponents determined in such a way has been examined through various techniques, like constructing the modified Arrott plot, applying the scaling law on the isothermal magnetization curves, and comparing the values with those obtained from the Kouvel-Fisher model. The resulting values of the exponents were estimated to be = 0.45(2), = 1.31(5), = 3.9(2) and = 0.69(1), close to the values predicted by the mean field theory. Hence, we concluded that the exchange interaction is of long-range type.

Modeling the Magnetocaloric Effect of La0.67Pb0.33MnO3 by the Mean-Field Theory

2018 ◽  
Vol 31 (11) ◽  
pp. 3717-3722 ◽  
Author(s):  
Mohamed Hsini ◽  
S. khadhraoui ◽  
N. Zaidi ◽  
Ziyad A. Alrowaili
Keyword(s):  
Field Theory ◽  
Magnetocaloric Effect ◽  
Mean Field Theory ◽  
Mean Field ◽  
The Mean

Microscopic description in the Gaussian approximation of the nematic-isotropic phase transition

1991 ◽  
Vol 69 (2) ◽  
pp. 154-160
Author(s):  
P. A. Pashkov ◽  
S. I. Vasiliev
Keyword(s):  
Field Theory ◽  
Phase Transition ◽  
Gaussian Approximation ◽  
Dimensional Space ◽  
Mean Field Theory ◽  
Mean Field ◽  
Isotropic Phase ◽  
Cluster Approximation ◽  
Field Fluctuations ◽  
The Mean

The nematic-isotropic phase transition of a system of nonpolar rodlike molecules is considered. The mean-field theory is extended to take into account the local field fluctuations in the Gaussian approximation. The calculations are performed in the five-dimensional space of the order-parameter components. The numerical results are obtained for the lattice system of molecules and compared with the calculations in the mean-field theory, cluster approximation, and Monte-Carlo simulation data.

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