Theoretical analysis of magnetic properties and the magnetocaloric effect using the Blume-Capel model

IF 0.9 4区物理与天体物理 Q4 PHYSICS, CONDENSED MATTER

Condensed Matter Physics Pub Date : 2022-03-26 DOI:10.5488/CMP.25.13702

Samuel de Oliveira, R. Morais, J. P. Santos, F. Barreto

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引用次数: 2

Abstract

This work investigates the magnetic properties and the magnetocaloric effect in the spin-1 Blume-Capel model. The study was carried out using the mean-field theory from the Bogoliubov inequality to obtain the expressions of free energy, magnetization and entropy. The magnetocaloric effect was calculated from the variation of the entropy obtained by the mean-field theory. Due to the dependence on the external magnetic field and the anisotropy included in the model, the results for the magnetocaloric effect provided the system with first-order and continuous phase transitions. To ensure the results, the Maxwell relations were used in the intervals where the model presents continuous variations in magnetization and the Clausius-Clapeyron equation in the intervals where the model presents discontinuity in the magnetization. The methods and models for the analysis of a magnetic entropy change and first-order and continuous magnetic phase transitions, such as mean-field theory and the Blume-Capel model, are useful tools in understanding the nature of the magnetocaloric effect and its physical relevance.

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用Blume-Capel模型对磁性能和磁热效应进行理论分析

本文研究了自旋为1的Blume-Capel模型的磁性和磁热效应。利用Bogoliubov不等式中的平均场理论，得到了自由能、磁化强度和熵的表达式。磁热效应是由平均场理论得到的熵的变化来计算的。由于依赖于外加磁场和模型中包含的各向异性，磁热效应的结果为系统提供了一阶连续相变。为了确保结果，在模型呈现磁化连续变化的区间使用了麦克斯韦关系，在模型呈现磁化不连续的区间使用了克劳修斯-克拉珀龙方程。分析磁熵变化和一阶连续磁相变的方法和模型，如平均场理论和Blume-Capel模型，是理解磁热效应本质及其物理相关性的有用工具。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Condensed Matter Physics 物理-物理：凝聚态物理

CiteScore

1.10

自引率

16.70%

发文量

审稿时长

1 months

期刊介绍： Condensed Matter Physics contains original and review articles in the field of statistical mechanics and thermodynamics of equilibrium and nonequilibrium processes, relativistic mechanics of interacting particle systems.The main attention is paid to physics of solid, liquid and amorphous systems, phase equilibria and phase transitions, thermal, structural, electric, magnetic and optical properties of condensed matter. Condensed Matter Physics is published quarterly.